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1. A Systems Approach to High Yields, Efficiency and Profits in Corn, Wheat and Doublecropped Soybean RotationUsing a systems approach friendly to the environment, a three-crop/two-year no-till system has shown significiant yield increases in a three-year research project conducted at the Poplar Hill Research and Education Facility in Quantico, Maryland. In each case, corn, wheat, and doublecropped soybean yields exceeded average yields produced on Maryland's Delmarva Peninsula. Instrumental in producing these superior yields were enhanced fertility, supplemental water, and appropriate variety selection... |
2. Active and Passive Spectral Sensing for Predicting the Optimum Nitrogen Rate and Timing in CornThere are many in-season plant diagnostic tools available for predicting the rate and timing of in-season nitrogen fertilizer in corn (Zea mays L.). However, soils in Southern Minnesota are generally high in organic matter and can carry over nitrate- nitrogen from one season to the next. Subsequently, there is oftentimes sufficient soil nitrogen early in the growing season to supply much of the crop requirement, limiting the use of sensor-based N management tools. Past wor... T. Nigon, D. Kaiser, C. Yang, D. Mulla |
3. Active-Optical Reflectance Sensing Evaluated for Red and Red-Edge Waveband SensitivityUncertainty exists with corn (Zea mays L.) N management due to year-to-year variation in crop N need, soil N supply, and N loss from leaching, volatilization, and denitrification. Active-optical reflectance sensing (AORS) has proven effective in some fields for generating N fertilizer recommendations that improve N use efficiency. However, various sensors utilize different wavebands of light to calculate N fertilizer recommendations making it difficult to know which waveband is most sens... G. Bean, N. Kitchen, J. Camberato, R. Ferguson, F. Fernandez, D. Franzen, C. Laboski, E. Nafziger, J. Sawyer, P. Scharf, J. Schepers, J. Shanahan |
4. Agronomic Evaluations of MAP and DAPThe old issue of MAP vs DAP has resurfaced. Although the renewed interest in this issue stems from manufacturing considerations, it would seem appropriate at this point to review our current understanding of agronomic characteristics of these two materials. One of the last reviews done on this subject was part of a review of P sources written by Larry Murphy and presented at the 1979 North Central Extension Industry Soil Fertility Workshop entitled "MAP, DAP, Poly and Rock. The amount of new res... |
5. Ammonia Band Spacing Effects on Ammonium Persistence in the BandResults from four field experiments (1991 and 1992) showed that anhydrous ammonia (AA) concentration in the band increased NH4-N persistence in the Hord and Sharpsburg soils in 1992, but not in the Cass and Zook soils in 1991. In 1992, average half-life across both soils was increased from 14 days when applied in a 38 cm spacing to 66 days when applied in a 152 cm spacing (every other row) at the high application rate (224 kg N ha-'). A half-life of 66 days indicates 25% of the applied AA would ... |
6. An Integrated Approach to Understanding Poultry Litter Use in Corn-Soybean Production SystemsThe majority of poultry litter (PL) in Kentucky is generated in the western third of the state, the same area that produces approximately 80% of corn, soybean, and wheat. This PL is applied to row crop fields as a nutrient source. Producers and commodity board representatives were concerned with reported nutrient availability coefficients, nutrient value, and long-term use of PL. Four field sites in a NT corn-soybean rotation were identified in the fall of 2012 with low to medium soil test va... E. Ritchey, E. Haramoto, C. Bradley |
7. Arbuscular Mycorrhizal Fungi and Their Role in Modern AgricultureArbuscular mycorrhizal (AM) fungi are obligate symbionts of over 90% of land plants, including most of the worlds economically important food crops. This symbiosis is believed to have evolved some 400 million years ago concurrentwith land plant flora to assist in phosphate uptake, an ion of poor mobility in soil. A key feature of the symbiosis is the ‘arbuscule’, a fungal organ that penetrates root cortical cells and forms a convoluted peri-arbuscular membrane of large surfac... R. Drijber |
8. Basic Concepts of Soil Acidity and LimingWith today’s cropping systems utilizing high rates of N fertilizers, most Midwestern soils require periodic applications of aglime or other liming materials for optimum crop production. Liming has several beneficial effects: 1) it reducesaluminum or manganese toxicity, harmful or potentially toxic conditions which can develop in acid soils; 2) it increases the availability of some of the essential nutrients; 3) it replaces the supply of calcium and magnesium essential for plant gro... D. Mengel |
9. Can a Winter Rye Cover Crop Mitigate Nitrate Leaching from Corn Production on Irrigated Coarse Textured Soils?Minnesota has approximately 500,000 acres of irrigated coarse textured soils. These soils are very productive but are highly vulnerable to nitrate (NO --N) leaching and ground water contamination. In these soils, most of the NO --N leaching losses take place in early spring and late fall, when precipitation is high and crops have limited water and nutrient uptake. The objectives of this study are 1) quantify the capacity of rye (Secale cereal L.) as a cover crop to mi... N. Ricks, F. Fernandez, J. Baker |
10. Can Narrow Row Spacing be Used to Manage Higher Planting Densities of Corn?The average U.S. corn (Zea mays L.) plant density has increased 988 plants ha-1 year-1. As this trend continues, narrow row spacings can be used to increase the distance between plants within a row and provide greater plant spacing across a given area. The overall goal of this study was to understand the relationship between row spacings and planting densities across different hybrids on corn growth and grain yield. The experiment was conducted in Champaign, IL to evaluate the inter... B. Bernhard, F. Below |
11. Cereal Rye and Hairy Vetch Cover Crops for Improving Soil and Water QualitySoil and water quality benefits of cover crops (CCs) have been inferred only from plot scale studies. Replicating cover crops at the watershed scale and expecting similar results to that of plot scale studies need further research. Therefore, cover crop study at Southern Illinois was carried at the plot as well as the watershed scale. The objectives of plot scale study were (i) to evaluate the contribution of fertilizer and soil organic matter (SOM) to N leaching under corn/soybean ... S. Gurbir, K. Williard, J. Schoonover, R. Cook, R. Mcelroy |
12. Combining Nitrification Inhibitor TechnologiesTechniques exist for the partial control of nitrification, but few studies have determined the effectiveness of combining more than one technique. A series of experiments compared the nitrification rate of urea granules as influenced by granule size (0.01, 0.1, and 1.0 g/pellet) and dicyandiamide (DCD) addition (0, 1, 2, 5, and 10% of N) . A second series of experiments measured the interactive effects of DCD and ammonium thiosulfate (ATS) on nitrification of liquid fertilizers. Both experiments... |
13. Comparing the Performance of Preplant and Presidedress Soil Nitrate Tests for the North-Central RegionSoil nitrate (NO3-N) testing is a recommended best management practice (BMP) for adjusting corn N fertilization rates across the North-Central region. Several approaches to soil NO3-N testing are used and vary in both recommended time and depth of sampling (Hergert, 1987). Nitrate is very mobile in soil and is subject to either loss from leaching and denitrification or gain from net mineralization of crop residue and manure. The processes that govem nitrate accumulation in soils are most active ... |
14. Comparison of Ground-Based Active Crop Canopy Sensor and Aerial Passive Crop Canopy Sensor for In-Season Nitrogen ManagementCrop canopy sensors represent one tool available to help calculate a reactive in-season nitrogen (N) application rate in corn. When utilizing such systems, corn growers must decide between using active versus passive crop canopy sensors. The objectives of this study was to 1) determine the correlation between N management by remote sensing using a passive sensor and N management using proximal sensing with an active sensors. Treatments were arranged as field length strips in a randomized comp... J. Parrish, R. Ferguson, J. Luck, K. Glewen, L. Thompson, B. Krienke, N. Mueller, T. Ingram, D. Krull, J. Crowther, T. Shaver, T. Mieno |
15. Comparison of Mehlich-3, Olsen, and Bray-P1 Procedures for Phosphorus in Calcareous SoilsFertilizer recommendations for P generally are based on soil testing. Although a variety of soil tests are reliable for evaluating plant available P of neutral or slightly acid soils. there is still uncertainty about appropriate soil tests and soil-test interpretations for calcareous soils. The Bray-P 1 and Olsen methods are the most widely used soil-test P methods in the North Central region. Extensive research has shown that the Bray-P1 test is reliable on neutral or acid soils but that it ten... |
16. Corn grain nitrogen and yield with foliar nitrogen application at early reproductive growth stageLate fungicide applications in corn with the use of high clearance equipment create the opportunity for additional foliar fertilizer applications. The objectives of this study were to (1) evaluate the benefit of fungicide applications on yield and grain N in combination with foliar N applications and (3) assess the value of foliar N the application using N sources with urea- formaldehyde/triazone during the VT-R1 growth stage. This experiment was conducted at 6 locations in 2016 and 2017... A. Stammer, D. Ruiz diaz |
17. Corn Production as Affected by Daily Fertilization with Ammonium, Nitrate, and PhosphorusManipulation of N fertilization to control NH,+/NO,' ratios in the soil can affect corn (Zea mqs L.) growth and yield. Field study of these effects, however, has been difficult to conduct because nitrification of NH,+ andlor NO, leaching often occurs during the growing season. The objectives of this 4-year field experiment, were to investigate the effects of daily fertilization with various N sources and P on corn growth and yield. Pioneer 3343 was fertilized with solutions of urea (U), NH,CI, C... |
18. Cover Crops and Tillage Interaction on Claypan Soils of Southern IllinoisIncreased nutrient leaching due to agricultural practices such as tillage and fertilization is a significant environmental concern. Nitrogen (N) mineralization stimulated by tillage can increase the risk for nitrate leaching before subsequent crops have an opportunity to take up the N released by microbial activity. An alternative measure for reducing potential nutrient loss via leaching and runoff is use of cover crops (CCs). A field experiment was conducted at the Southern Il... S. Gurbir, J. Schoonover, K. Williard, K. Gauge |
19. Crop P Nutrition and the Three Pillars of Soil Health: Less Soil Disturbance, Greater Crop Diversity, Organic Nutrient SourcesThe soil health initiative is built around a number of principles, but three central components are reduced soil disturbance, especially no-tillage; increased crop diversity, especially cover crops; and greater use of organic materials (manures, composts, etc.) as nutrient sources. Reduced tillage intensity causes temperate soil environment changes such that oxidation of organic matter is slowed and phosphorus (P) stratification is reinforced. Cover crop insertion heightens P cycling, ge... J. Grove |
20. Crop Residue and Fertilizer Management Effects on Soybean, Wheat, and Grain Sorghum in Eastern KansasRemoval of crop residue is being considered for many non- agricultural uses. The agronomic consequences of these practices are not fully known, especially for different levels of fertilizer management. An experiment was begun in eastern Kansas in 1980 to determine the effects of returning different levels of crop residue on soil properties and crop yields in a soybean-wheat-grain sorghum rotation, fertilized with different amounts of N-P-K fertilizer. Crop residue treatments included residue rem... |
21. DAP vs MAP Manufacturing/Marketing ImplicationsOver the past several years, discussions on the suitability of monoammonium phosphate (MAP) and diammonium phosphate (DAP) as P sources for crop production have been common. In addition to agronomic principles, these discussions have often focused on what the future holds on the availability of these two materials in the marketplace. This discussion will deal with manufacturing and marketing influences on future availability/use, while agronomic comparisons will be made elsewhere. To some, phosp... |
22. Do Split-Nitrogen Applications in the Midwest Affect Corn Nitrogen Uptake and Grain Yield?It is hypothesized that split-nitrogen (N) relative to single near-planting applications improve corn (Zea mays L.) grain yield and nitrogen recovery efficiency, which can lessen environmental impacts of fertilization. However, these hypotheses have not been fully tested. A 49-site-year study across eight US Midwestern states over three years was conducted to compare near-planting (Single) and split-N (Split) applications. Three N application timings were evaluated [Single near plan... J. Clark, F. Fernandez, J. Camberato, P. Carter, R. Ferguson, D. Franzen, N. Kitchen, C. Laboski, E. Nafziger, J. Sawyer, J. Shanahan |
23. Effect of Date of Planting on Method of P Performance for Winter WheatSeed and knifed P (dual placement) have usually performed similarly on winter wheat (Triticum aestiviuum L.), but in some years seed applications have been found to be superior to knifed P. Three winter wheat experiments were established on low available P soils in southeast Nebraska to study the effect of date seeding on seed and knifed P (dual placement) performance. Three rates of P (11, 22, and 33 kg P ha-') were seed and knife applied on three seeding dates in 1987. Data indicated that the ... |
24. Effect Of High Carbon Char in Conjunction with Composted Manure and Urea on Corn YieldAn integrated approach to optimize fertilizer input through use of high carbon char (also called cinder), a by-product from a local industry in Western Nebraska, was set up for determination of optimal rate of char along with a given nitrogen (N) fertilizer or composted manure on corn (Zea mays L.) yield. Char is a potential soil amendment, since it contains around 30% total carbon (C) in addition to many essential plant nutrients. The experiment was started in 2016 in sandy loa... D. Panday, B. Maharjan |
25. Effect of NBPT-Amended Urea and UAN on No-till Corn in Northern IllinoisField evaluations of the urease inhibitor N-(n-butyl) thiophosphoric triamide (NBPT) have been extensively conducted across the USA with encouraging results. Most response data collected to date has been with corn. In this report results from 7 'years of experiments at two southern Illinois locations (Belleville and Carbondale) are presented. NBPT addition to broadcast-placed urea, when evaluated across N rates and locations, gave no- till corn yield increases averaging 8.4 bulac in 13 experimen... |
26. Effects of Residue Density, Strip Tillage, and Starter K on No-till Corn Grown in Wheat StubbleField studies were conducted in 1992 to 1994 at 2 locations in southern Illinois to evaluate the influence of wheat straw residue density and stl-ip-tillage vs no-tillage on corn growth and yield. Corn growth and resultant yield is frequently reported by producers to Se depressed in the residues of a previous wheat crop. Allelopatliy is thought to be at least partially involved. The objective of the research was to evaluate straw level (removed, remain non-modif ied, and doubled), strip tillage,... |
27. Effects of Residue Management on Fertilizer use Efficiency on Corn in the Western Corn BeltInterest in residue management began in parts of the Great Plains following the "dirty thirties" when the government responded to wind and water erosion problems by creating the Soil Conservation Service. Stubble mulch in winter wheat production areas evolved into no-till as herbicides becan~e available. Interest in limited or no till systems in the Corn Belt began in the 1950's. Higher residue levels are required to reduce erosion while maintaining soil productivity but an additional reason is ... |
28. Evaluation of Agricultural Lime and Pelleted Lime to Increase Soil pH and Crop YieldAgricultural lime (aglime) is applied to increase pH of acidic soils to values optimum for crop production, and its effectiveness is affected mainly by it calcium carbonate (CaCO3) equivalent (CCE) and fineness. Availability and use of pelletized limestone has increased in recent years, but there is limited information about its effectiveness. Six field trials were established in 2014 at acidic Iowa soils (pH 4.9-6.1) with contrasting texture and organic matter. Treatments replicated three ti... A. Mallarino, M. Haq |
29. Fertilizer management and cover crop effects on phosphorus use efficiency, environmental efficiency and crop yieldPhosphorus loss from agricultural production is a significant contributor to the degradation and contamination of surface and ground waters. To help protect these waters, it is vital to maximize agronomic and environmental efficiency of phosphorus in the cropping system. The objective of this study was to quantify the effects of cover crops and different phosphorus fertilizer management practices on nutrient use efficiency, environmental efficiency and yield in a no-tillage corn-soybean rotat... R. Carver, N. Nelson, G. Kluitenberg, K. Roozeboom, P. Tomlinson |
30. Fertilizer use in the Future- A University PerspectiveOver the last few years, several agrodc, economic, political, environmental and sociological trends have begun to eruerge which will significantly affect fertilizer use in the next decade and perhaps beyond. The wide-spread use of fertilizers is a relatively recent developmt. Over the past 40 years, farmers repeatedly saw the benefits of fertilizer applications and developed a faith in their need. Hwever, the 1990's are not the 1950's. As point& out by Dean L. M. Walsh in a recent paper in Deale... |
31. Field Scale Fertilizer Recommendations and Spatial VariabilityFertilizer is usually applied at a single constant rate across a field. However, soil fertility may vary considerably within a field. Soil test calibrations (ie recommended fertilizer versus soil test ) are usually obtained from sites with low spatial variability of soil test values (ex. small plots ). These calibrations are then assumed to be valid for large fields with variable soil fertility. The effects of variable soil fertility on the relationship between average crop yield response, avera... |
32. Forage Quality Management- A Key to Successful Cattle Nutrition ProgramsIn 1992, the USDA reported 59.6 million acres were harvested for hay with an average yield per acre of 2.5 ton per acre. These values gave a projected total yield of 149.1 million tons of harvested hay. Using an average market price of $72.10 per ton, total value of hay produced exceeded 10.5 billion dollars. Also in 1992, alfalfa production represented over 50 percent of the forage harvested with 79.6 million tons produced. In addition to stored forage. pasture is also a significant source of f... |
33. Hybrid and Potash Effects on Root Growth in Ridge-till CornPotassium deficiency symptoms often appear in ridge-till and no-till corn even when soil test values for potassium are high. Certain hybrids are morc sensitive to the problem than others. Two techniques were used to assess root activity arid density in a three year experiment at the West Central Experiment Station, Morris, MN. We compared two tillage systems (fall chisel and ridge till). two hybrids (Pioneer 3732 and 3737) and three fertilizer treatments (control and 40 IbIA banded or broadcast ... |
34. Identifying Which Management Factors Have the Greatest Impact on Soybean YieldsSoybean [Glycine max (L.) Merr.] grain yields are the final products of numerous factors that affect crop growth and development during the growing season; therefore, it is critical to understand the interactions of these factors evaluated as a whole in order to efficiently maximize yield and exploit the yield potential of modern soybean varieties grown under increased levels of management. The objective of this experiment is to evaluate the synergies between several manag... T. Beyrer, F. Below |
35. Impact of Excess Water on N LossThe impact of excess soil water on N use efficiency by corn was evaluated over several years at four locations in Illinois. At each location, 0, 4, or 6 inches of water was applied in late May to soils that were at field capacity. Prior to the addition of the excess water, potassium nitrate was applied at rates ranging from 0 to 200 Ib Nlacre. On medium to heavy textured soils, the number of days when soil moisture was at saturation provided a good estimate of the magnitude of N loss. Yields we... |
36. Improving PSNT Based Sidedress N Recommendations for Corn with Site Specific FactorsThe pre-sidedress soil nitrate test (PSNT) has been found to be a valuable tool for improving nitrogen recommendations for corn grown in humid regions of the country. The PSNT has been especially useful for nunaging N on fmls where organic sources of N, like animal manures are important. This test was proposed by Magdoff et al. in 1984 and has been studied extensively since then (Magdoff et al., 1990; Roth et al., 1992; Fox et al., 1989; Blackmer et al., 1989; Klausner et a]., 1993, and Meisinge... |
37. Influence of phosphorus management on potential for soluble phosphorus loss through leachingThe over application of phosphorus (P) fertilizers in agricultural systems may pose a threat to water quality due to the loss of dissolved P to fresh water bodies leading to eutrophication. The objectives of this study were to evaluate the potential for water soluble P loss from top soil (0-6 inches) across a range of initial soil test phosphorus (STP) levels, soil types, and leaching volumes; and to determine if P leaching loss could be predicted with existing soil P tests. Intact soil colum... L. Leverich, D. Kaiser |
38. Influence of Potassium, Sulfur, and Zinc Fertilizer on Corn and Soybean Grown on High Tetsing SoilThe influence of potassium, sulfur and zinc fertilizer on corn and soybean yields grown on high testing soils was studied at two locations in Eastern South Dakota over a period of six years. Treatments were 50 Ibla K,O, 25 Ibla sulfur and 5 Ib/a zinc. The treatments were applied to the same plots at each location every year. Soil test levels were in the high range for all elements in question and additional nutrients would not have been recommended by the South Dakota State University Soil Testi... |
39. Influence of Water Treatment Lime Sludge on Soil pH and Crop YieldsSoil pH levels are decreasing in extreme Eastern South Dakota. To test the effectiveness of water treatment lime sludge in raising soil pH and crop yields, a liming study was established at four locations with pH levels of 5.7 or less. The lime sludge applied at 3 tons per acre raised soil pH to neutral and maintained it at neutral for the 4 year duration of the study. Crops grown at the various sites included soybeans, corn, spring wheat, winter wheat and forage sorghum. Although there was a t... |
40. Integrated Farm Management Demonstration Program in IowaThe Integrated Farm Management (IFM) Demonstration Program was established by the landmark 1987 Iowa Groundwater Protection Act. The five-year program, funded through 1992, is a cooperative effort involving various state agencies, Iowa State University and Iowa farmers. The program coordinators, many of whom are Iowa State Extension Service staff and scientists, work with farmers to help them implement best available technology that protects the environment and conserves energy. The goal of the ... |
41. Integrating Management Zones and Canopy Sensing for Improved Nitrogen Recommendation AlgorithmsActive crop canopy sensors have been studied as a tool to direct spatially variable nitrogen (N) fertilizer applications in maize, with the goal of increasing the synchrony between N supply and crop demand and thus improving N use efficiency (NUE). However, N recommendation algorithms have often proven inaccurate in certain subfield regions due to local spatial variability. Modifying these algorithms by integrating soil-based management zones (MZ) may improve their accurac... J. Crowther, J. Parrish, R. Ferguson, J. Luck, K. Glewen, T. Shaver, D. Krull, L. Thompson, N. Mueller, B. Krienke, T. Mieno, T. Ingram |
42. Iowa Soybean Nitrogen Fixation Consider in Nitrogen BudgetsSoybean (Glycine max) is one of the most important agricultural commodities grown in Midwestern states of the US and some other parts of the world. Like many other legumes, soybean can associate symbiotically with nitrogen (N) fixing bacteria, which can transform the N2 from the atmosphere into NH3 a more available N form, through a process known as biological N fixation (BNF). However, BNF is an energy expensive process for soybean that requires carbohydrates fr... S. Cordova, R. Dietzel, M. Licht, S. Archontoulis, M. Castellano |
43. Late-Split Nitrogen Application On CornThe practice of applying a last (or additional) increment of N fertilizer during late vegetative growth of corn using high-clearance equipment has grown rapidly in the last few years, despite the absence of evidence supporting the profitability of this practice. We established a set of trials in which a range of N rates from 0 to 280 kg/ ha were applied as UAN solution, either all at planting or with 56 kg N reserved and hand-applied at the base of the plants at tasseling (late-spli... D. Rapp, E. Nafziger |
44. Managing Field Soil Fertility VariationsFertilizer and crop production inputs are most often applied as a single blanket application rate across an entire field. Yet variations in field conditions including soil characteristics and measured crop yield are known to exist and often in a systematic, fashion. Grid soil sampling for fertility variations, plant analyses, and color photography were found to be most useful tools for assessing manageable field variations. Increased profit and environmentally sound improvements in fertilizer us... |
45. Manure and Fertilizer Management Influence on Soil Nutrient Levels and Grain Yields in Eastern South Dakota from 2003 to 2014Concentrated animal feeding operations (CAFOs) are required to hold a manure management permit in South Dakota. The permit encompasses available nutrients from manure, crop nutrient use and removal, soil test nitrate-N, and phosphorus and land availability for approved nutrient application rates. The management plan determines if nitrogen or phosphorus based manure application rates are used. Most CAFO’s start out following the nitrogen based plan as soil test phosphorus (P) levels... A. Bly, S. Berg, R. Gelderman, B. Rops, P. Sexton, C. Morris |
46. Manure Brokerage in OhioIn Ohio there are several counties where annual manure production exceeds the requirements of all crops grown in the county. Poor distribution of this manure has created instances where soils have become overloaded with phosphorus, contributing to the phosphorus load of surface waters and creating the potential for long term release of phosphorus into states waters. Nitrogen also becomes an environmental concern as excess nutrient loads are placed on soils, nitrogen is found leaching through til... |
47. Michigan Right-to-Farm- Generally Accepted Agricultural and Management Practices for Nutrient UtilizationThe following is a summary of Michigan's Right-To-Farm nutrient management practices. These practices were adopted by the Michigan Agricultural Con~mission in January of 1993. Crop producers who voluntarily follow these practices are provided protection from public nuisance disputes under Michigan Public Act 93 of 1981 as amended, The Right-To-Farm Act, Michigan Department of Agriculture. A complete copy of the Right-To-Farm document may be obtained by writing to Robert Craig. Michigan Departmen... |
48. Minnesota Long-Term Phosphorus Management Trials-Phase II: Sufficiency Level vs. Build and Maintain ApproachesCurrent Minnesota P recommendations for corn and soybean are based on the Sufficiency approach. In recent years, it has been questionable that the Sufficiency approach could maximize potential grain yield in today’s agricultural systems. The objective of this research was to establish six long-term experiments across Minnesota to test phosphorus management strategies on soils with a defined long-term phosphorus history. Four soil test P (STP) Interpretation Classes&n... D. Kaiser |
49. Nitrate Soil Testing Correlation and Calibration Eastern Corn BeltCurrent economic and environmental concerns have increased the interest in developing methods to help manage nitrogen (N) fertilizers as efficiently as possible. There is a concern that fertilizer N that remains in the soil following harvest may be leaching below the root zone of crops and eventually ending up in groundwater. Agronomists throughout the corn belt are actively evaluating methods to manage N fertilizer as efficiently as possible.... |
50. Nitrate Testing ClinicsThirty-eight nitrate testing clinics were held in 36 Michigan counties in the spring of 1989. A mobile testing van was equipped for nitrate analysis of soil and water samples. Over 2,200 soil samples and 1500 water samples were analyzed for nitrate N using the nitrate ion-specific electrode. More than 50 percent of the soil samples . contained less than 30 lb of nitrate N in the surface two feet. Only 35 percent of the 1,100 fields were given a nitrogen credit based on the residual nitrate test.... |
51. Nitrification Inhibitor Value in Irrigated Corn: Insights From a Long-term StudyProper nitrogen (N) nutrition is key to optimizing corn yields. Due to its dynamic behavior in soils, N can be lost through different pathways and negatively impact corn production. Nitrification inhibitors (NI) decrease the rate of ammonium transformation to nitrate in the soil, potentially decreasing denitrification and leaching potential. However, NI only has a positive effect on yield if environmental conditions are conducive to loss to the point of N becoming limiting to crop p... L. Bastos |
52. Nitrogen and Potassium Interactions in CornExtensive research in the North Central region has investigated separately nitrogen (N) and potassium (K) fertilizer management for corn. However, there is scarce information available about how N and K interactions affect corn grain yield and nutrient uptake. The objective of this study was to evaluate the effects of various combinations of N and K rates on corn yield, N and K tissue concentrations, and N and K removed with grain harvest. Two trials with continuous corn were conducted from 2... J. Hirniak, A. Mallarino |
53. Nitrogen and Water ManagementIt is difficult to separate N and water management when developing improved management systems for irrigated corn production. This is because adequate supplies of both N and water are critical for crop growth, but excesses of either or both can threaten ground water quality. Several N and water management systems were established at the Nebraska Management Systems Evaluation Area (MSEA) project to evaluate the impact of improved irrigation and N fertilizer management practices on production and... |
54. Nitrogen Fertilizer For SoybeanConcern about soybean’s ability to provide energy to fix adequate N while still producing high yields has led to renewed interest in in-season use of N fertilizer. We conducted a series of fertilizer N timing experiments in Illinois, in different soil types with a range of yield potential. There were few responses to N in silt loam soils, with unfertilized check yields ranging from 4,108 to 6,125 kg/ha, though applying the same N increment four times increased yield sig... J. Vonk, E. Nafziger |
55. Nitrogen Management for Cool Season Grass ProductionStudies were initiated in 1985 on established smooth bromegrass and tall fescue to evaluate urea granule size effects on forage production and quality. Other work, evaluating N source by previous source effects and UAN placement methods and the addition of ATS, was conducted on established smooth bromegrass. Nitroger1 rates were also evaluated in all these studies, and the addition of N significantly increased forage yields and N concentrations in each study. Use of large (1.0g) urea granules pr... |
56. Nitrogen Management for Profitability and Groundwater ProtectionSugarbeet production practices have changed drastically in the last two decades in Minnesota and North Dakota. Changes in grower payment systems mandated change to production of high sugar content low impurity level beets. Development, refinement and extensive use of the soil nitrate-N test in concert with the sugar company quality payment program resulted in greatly reduced N fertilizer use while increasing crop yield and quality.... |
57. Nitrogen Management for Winter Wheat in MissouriEight site years of data have been collected to evaluate nitrogen rate and timing for intensively managed winter wheat in Missouri. Variables have included rates up 160 lbs N per acre applied as all fall, all spring, or split in a fall and spring or fall plus two spring applications. Results have pointed to the split applications of rates at 80 to 120 lbs N per acre as providing greatest consistency and economic return to the grower. Maximum yield has generally been obtained with the 3 way split... |
58. Nitrogen Soil Test for Corn in OntarioIt is generally believed that for high yielding crops such as corn. the N requirements are much larger than variations in the N supplying capacity of soil. In Ontario, fertilizer N recommendations are based on the requirements of the crop and, for some crops, the expected yield goal. Nitrogen credits are given for past management such as manure application and legumes in rotation. The credits are deducted from the economic rate of N. In a recent analysis of all existing fertilizer N crop respon... |
59. Nitrogen Source Affects Manganese Nutrition of No Till CornA study evaluating response of no-till continuous corn to different rates of N as injected anhydrous ammonia and broadcasted urea-ammonium nitrate solution (UAN) was conducted on a Canfield silt loam near Wooster, Ohio. Repeated use of anhydrous ammonia on this naturally acid soil resulted in relatively large concentrations of Mn (often > 200 ug/g) in corn plant ear leaves at silking. Ear leaf Mn concentrations were less when UAN was used. For both N source treatments, ear leaf Mn concentrations... |
60. Nitrogen Test Development Soil N Levels in 1989The developnent of a N test that can be used for fertilizer recamrendations of corn in the eastern areas of Minnesota is needed for environmental and econcmic reasons. A multi-site project was initiated in 1989 to extensively examine soil sampling time and depth as well as N forms in the soil. This will then enable statistical models to be develaped using one or mre of the variables. A subset of the entire project is reported--concentrating on the sites allowing the calibration of the soil N tes... |
61. Nutrient Management and Starter Fertilizer for No-till CornNo-till corn acreage has steadily increased in Illinois. No-till presents unique problems of nutrient stratification, increased surface residue, and cool, wet soils which may influence nutrient availability. Two experiments were initiated in 1993 at 4 locations to evaluate the response of no-till corn to: 1) primary N applications of anhydrous ammonia preplant, UAN broadcast preplant, and ammonia sidedressed at V6; 2) starter fertilizers with factorial combinations of N, P, and K banded 2 inches... |
62. Nutrient Management Following CRP- Concerns and On-Going ProjectsThe future of the Conservation Reserve Program (CRP) is uncertain as this paper is being prepared, however, most agree that at some point a significant acreage currently in CRP will be brought back into production. The peak of contract expirations for the 36 million acres of CRP will occur in the fall of 1996 with the first contracts originally due to expire in 1995 (Figure 1). Many of the Northcentral states have substantial CRP acreage's making post-CRP management an important topic for this r... |
63. Pass--An Improved System for Combining Dris and Sufficiency Range Approaches to Plant AnalysisThe University of Wisconsin Soil & Plant Analysis Lab (UW-Lab) includes both the Sufficiency Range (SR) and the Diagnosis and Recommendations Lntegrated System (DRIS) interpretations in plant analysis reports. The UW-Lab added the DRIS to its routine plant analysis program in 1992. Soon after its introduction, the DRIS appeared to be diagnosing Ca as yield-limiting in many cases where the SR interpreted Ca as sufficient. The DRIS diagnosis of Ca as deficient also contradicted previous research w... |
64. Phosphorous Management for Wheat ProductionProfitable wheat production depends on many factors, including a sound phosphorus (P) management program. Except for sunlight and water, soil fertility generally represents the most limiting factor in crop yields. Even with perfect weather and climatic conditions, a farmer that does everything right except to meet the nutrient needs of the crop will never reach optimum yield potential. Water, N, and P are generally the dominant yield limiting factors for wheat in the United States. Potassium, S,... |
65. Planting Equipment for No-tillPlanters or drills have to cut and handle the residue, penetrate the soil to desired seeding depth, and establish proper seed-to-soil contact. Keeping these three items in mind, a producer can evaluate the strengths or weaknesses of any piece of planting equipment and make any adjustments or changes necessary to make no-till planting successful. Fortunately. most currently available planters and drills can be used for no-till with few, if any, modifications. In the early days of no-till, produce... |
66. Preparing for No-till Planting into CRP LandAs CRP contracts expire, many producers are considering bringing the land back into crop production. In order to conserve soil and water, and to keep the soil building benefits of idling the land for ten years, no-till is the best production system to use. Tillage will destroy the soil structure that has built up from the freeze-thaw and wetting-drying cycles. In addition, it will plant surface weed seeds and stimulate seeds which have been buried for the last ten years. Tillage will also fluff ... |
67. Real-Time Soil Nitrate SensingIon-selective field effect transistors (ISFETs) have inherent features such as small dimensions. low output impedance. high signal-to-noise ratio, low sample volumes and the potential for mass production, which are required for a real time soil sensor. However, ISFETs have the disadvantage of long-term drift, which is diminished by the use of a Flow Injection Analysis (FIA) system. In fact, FIA and ISFETs are complementary since the small sample volumes and rapid response of ISFETs allow the mi... |
68. Recalibration of Potassium Requirements for Corn in North DakotaThe previous North Dakota potassium recommendations for corn were borrowed from central Corn Belt states, where the dry soil-based 1 M ammonium acetate extraction for soil test K was utilized with a critical K value of 150 ppm. This value was adequate before 2000 because corn production was limited to only a few counties in southeastern North Dakota, and soil test K values were commonly above 300 ppm. However, the intensification of corn production in these counties and an increasing acreage ... D. Franzen, J. Breker, M. Rakkar, A. Chatterjee |
69. Regionalizing Fertilizer Recommendations for North Dakota, South Dakota, and Western MinnesotaFertilizer recommendations have varied between adjacent states. The inconsistencies at state lines made educational efforts in soil fertility more difficult for companies doing business across state lines. In an effort to alleviate these problems, the agronomists working with fertilizer calibration data and recommendations from the three states of North Dakota, South Dakota and Minnesota put together a recommendation system which could be used in a large part of all three states. The basic "core... |
70. Regionalizing Nutrient Recommendations Indiana- Ohio- MichiganWHY THE INTEREST IN REGIONALIZE CROP NUTRIENT RECOMMENDATIONS ? 1) Wide variations in recommendations made to farmers by who makes them. a) by fertilizer dealers or sellers of product b) by llunbiasu consultants c) by soil testing labs d) by Universities e) by other governmental agencies 2) Philosophies are different in "What is best for Mr. Farmeru a) Sufficiency Level of Fertilization - "Feed the Cropw b) Build-up & Maintenance - "Feed the Soilt1 c) Cation Balance Method - "Keep everything in ... |
71. Relating Soil Properties to Spatial Variation of Phosphorus Critical LevelVariable rate (VR) fertilizer application has increased with proliferation of VR capable equipment. Current recommendations for VR phosphorus (P) application often assume that critical level is constant across a field adjusting only for spatial variation of soil P concentration. We conducted this study to determine whether variation in critical level, identified by relative yield of unfertilized to fertilized plots, could be explained by soil properties. In 2016, plots, me... J. Bowen |
72. Residual Soil NO3 N Variability Sampling Interpretation and Effect on Corn YieldResidual nitrate-N (NO3-N) in the soil profile (crop root zone) is seldom uniformly distributed. There is lateral as well as vertical variability. Numerous factors influence variability. Some of them are: 1) any factor that influences water movement through the soil such as - soil texture, compacted zone, topography and water distribution under irrigation - 2) previous crop, 3) fertilizer history (organic and inorganic sources) and 4) sampling time - caused primarily by factors influencing miner... |
73. Residue Management Systems in the Northern Corn Beltn the northern corn belt (Michigan, Wisconsin, and Minnesota) it is very important to minimize negative effects of crop residue (stand establishment and phenology). Soil cover in the row by crop residue (corn, small grain, or soybean residues) should be less than 10% in a strip 6 to 8 inches wide for corn. Mineralization of organic N sources such as legume residues, soil organic matter, and manure is reduced with systems that eliminate full width deep tillage such as ridge till, no till, or shal... |
74. Response of No-till Corn to Urease Inhibitors and Placement of N SourcesN(n-buty1)thiophosphoric triamide (NBPT) and ammonium thiosulfate (ATS) were investigated as urease inhibitors when added to urea and urea-containing N sources and applied to no- ill corn. Significant - f yield increases, some in excess of 20 bu ac , were observed with NBPT treatment of the N fertilizers. Lack of a yield response from NBPT, when it occurred, was usually associated with a rain event of major proportions soon after fertilizer application. ATS showed considerably less promise as a ... |
75. Returning Conservation Reserve Program Land to Crop Production: Weed Management ConsiderationsThe conservation reserve program (CRP) was formulated in the 1985 Food Security Act and established to help prevent soil erosion on more than one third of the crop acres in the United States (USDA, 1986). Soil erosion represents the greatest threat in agriculture to the environment. Nationally, an estimated 750,000,000 tons of soil have been conserved as a result of CRP representing an estimated annual savings of $2 billion in off-farm clearing of eroded soil. Other benefits of CRP wildlife enha... |
76. Root Growth and Phosphorus Uptake Affected by Fertilizer Management in Soybean and WheatPlant root growth patterns can be affected by nutrient and water availability. The objective of this study was to assess the effect of phosphorus (P) fertilizer management on soybean (Glycine max. L) and winter wheat (Triticum aestivum L.) root system growth and macro and micronutrients uptake. Two greenhouse studies were carried out at Kansas State University, Manhattan, Kansas under controlled environment. The experimental design... F. Hansel, D. Diaz |
77. Seed Inoculations and Nitrogen Fertilizer Trials with SoybeansCurrently there is a lot of interest in soybean seed inoculation. There are some new products on the market that are creating renewed interest in seed inoculation even on fields that have a history of soybean production. Some of the new inoculants have claims for higher potency, new and better strains of Rhizobium. higher numbers of Rlzizobiurn per gram of material, sterilized peat media, seed sticker additions and etc. Many companies are beginning to pay more attention to storage and handling o... |
78. Selected Soil Chemical Properties and Corn Grain Yield Under Different Manure SystemsThe Iowa Department of Agriculture and Land Stewardship estimated 1987 farm animal populations to be 4.6 million cattle and calves and 13.8 million hogs and pigs (26% of the nation's hogs). The animals produced about 141,987 tons of plant available N if 50% of the excreted N is available the first year of application. This amounts to 22 lb of N for every corn acre in Iowa. Most of the livestock operations are intensive with high populations of animals on a sniall land area. Nutrients in feed are... |
79. Should Corn Nitrogen Fertilizer Guidelines be Adjusted for Late N Fertilizer Applications?Late application of nitrogen (N) fertilizer is a topic that is receiving considerable attention. Previous research in Kansas has shown that split applications of N fertilizer can increase yield compared to applications at planting in some site years. This study was designed to investigate how N rate recommendation guidelines can be affected by splitting N fertilizer application with applications during late vegetative growth stage. Four corn study locations were established in North Central a... A. Stemmer, D. Ruiz diaz |
80. Site-Specific Management of N Fertilization in OntarioSignificant within field variability of soil properties, such as soil fertility, and plant growth have been well docome~ited. Standard soil testing practices and fertilizer recommendations which enco~npass an average soil test value for a field and a constant rate of fertilization will obviously result in certain areas of a field being either over or under fertilized. As indicated by Kachanoski and Fairchild (1995), for a single (constant) rate of fertilizer application, reconimendations based o... |
81. Site-Specific Management Research in MIssouri- Swamped in Spatial DataWith a maturing GPS technology, we have over the past couple of years become very enamored with producing maps on crop production fields. It wasn't long ago that the only map available was the soil map from county soil surveys. Continued sensor development and aerial photography and sensing, along with decreasing costs to store and manipulate spatial data, will mean that in the future measuring and mapping data will be the rule. There have been a lot questions raised regarding the minimum amount... |
82. Site-Specific Research in North DakotaSite specific fertilizer application is currently being practiced in the Red River Valley of North Dakota/Minnesota A study has been initiated to determine sampling practices suitable for North Dakota producers using sitespecific farming both within and west of the valley. Two forty acre fields were sampled in 1994 in a 110 ft. grid, separating each sample into 0-6" and 6-24" subsamples. Smaller grid sizes were also obtained at 10 and 2 ft. grid distances in selected areas of each field. Nitrate... |
83. Soil Organic Matter as it Relates to Soil Health and Plant NutritionTotal organic matter via loss on ignition is a standardized soil measurement in the North Central region. There is wide spread consensus that total organic matter is a very important indicator of the fertility of a soil, but how many farmers actually use total organic matter values from a soil test in an actionable way? An alternative approach would be to focus on the active fraction of organic matter. This is a small, but important pool that reflects the biologically available and ... S. Culman |
84. Soybean Seeding Rate and Nutrient Interactions on Growth and Yield in MichiganSoybean (Glycine max L. Merr.) prices are forecast to remain stagnant placing greater emphasis on production costs for growers across Michigan. Seeding rates and fertility inputs are two factors producers can manage to influence economic return. Field research was conducted in Richville and Lansing, MI in 2017 to evaluate biomass production and yield in response to nutrient inputs and help determine economically optimal seeding rates. The study was desig... T. Purucker, K. Steinke |
85. Starter Fertilizer Interactions with Corn HybridsThe objective of this study was to evaluate the response of corn hybrids grown in a dryland, no-tillage production system on a soil high in available phosphorus to starter fertilizer. Treatments were corn hybrids (5 in 1993 and 6 in 1994) grown with or without starter fertilizer. Starter fertilizer (30 Ib N and 30 Ib P,O,) was applied 2 inches to the side and 2 inches below the seed at planting. Nitrogen was balanced on all plots to give a total of 180 IbIA. Bray-I P level in the experimental ar... |
86. Stover Removal Effects on Continuous Corn Yield and Nitrogen Use Efficiency Under IrrigationCorn (Zea mays L.) residue or stover is harvested as supplemental feed for livestock and is a primary feedstock for cellulosic biofuels. Limited information is available on corn residue removal effects on grain yield under different nitrogen (N) fertilizer rates, irrigation rates and amelioration practices to minimize soil carbon loss and soil erosion. A study on a silt loam in south, central Nebraska (2011-2016) evaluated potential interactions between stover removal (residue r... M. Schmer, V. Jin, A. Sindelar, R. Ferguson, B. Wienhold |
87. Survey of Corn Response to Fertilizer Sulfur in MissouriAbstract Fertilizer sulfur (S) rate studies were conducted during 1991 and 1992 at 53 sites located throughout Missouri on soils that were primarily silt loam or heavier. Sites were selected on the basis of a high yield potential since a common belief among farmers and fertilizer dealers is that the greater crop S requirement of high yields exceeds the S supply from the soil and incidental sources. Either ammonium sulfate or ammonium thosulfate were applied at planting or wihn four weeks followi... |
88. Targeting Input Responses and Returns on Intensively-Managed Soft Red Winter WheatConsecutive years of record wheat (Triticum aestivum L.) yield (81 and 89 in 2015 and 2016, respectively), climate variability, and continued demand from Michigan’s milling and cereal industry have increased interest in intensively-managed (i.e. multiple-input) soft red winter wheat production systems. The objective of this study was to investigate the grain yield and economic profitability of several agronomic inputs across intensive (i.e., multiple- input) and traditiona... D. Quinn, K. Steinke |
89. The Conservation Reserve Program- Changes on the HorizonTen years ago, Congress passed the foundation of current conservation programs--the Food Security Act of 1985. Today, one program in particular, has exceeded many peoples' expectations. The Conservation Reserve Program (CRP) yas designed to take 40 - 45 million acres of highly erodible cropland out of production for a 10 - 15 year period. As the first CRP contracts begin to expire, Congress and the Administration are grappling with the program's future in the context of the 1995 farm bill. Will ... |
90. The Effect of Agricultural Management Practices on Labile Soil Carbon and Nitrogen in WisconsinAmid ever-increasing enthusiasm for soil health there remains uncertainty about how best to measure it, to interpret the results, and to adapt agricultural management accordingly. One factor of particular interest to farmers is the capacity of a soil to mineralize organic matter, making nutrients available to crops. This research takes a survey-based approach to identify how labile carbon (C) and nitrogen (N) – as permanganate oxidizable carbon (POxC), potentially mineralizable carbon (... G. Richardson, M. Ruark, E. Silva, M. Chawner, E. Olson, A. Radatz, C. Zegler |
91. The Effect of Tillage and Soil Test and Applied K on Corn and Soybean ProductionThe buildup-maintenance fertility concept for P and K has a strong theoretical basis, but much of the research from which it was derived was not designed to accurately determine the true maintenance requirement. Most of that research was confounded by an annual application at set rates irrespective of yield obtained. Experience in recent years has shown that on some soils the K soil test has not consistently accounted for past additions of fertilizer. In addition, applications equivalent to crop... |
92. The Importance of Soil Health and the Efforts of NRCSSince its inception in 1932, USDA-NRCS has worked with agricultural producers and landowners to address natural resource concerns, and improve long-term productivity on the nation’s private working lands. The mission of the agency is accomplished primarily through local field staff who provide technical assistance, and work with interested farmers and ranchers to develop conservation plans that improve identified resource concerns. In addition to site-specific technical&n... D. Chessman |
93. The Nitrate Soil Test in South DakotaThe nitrate nitrogen soil test has been used for more than 15 years for making nitrogen fertilizer recommendations in South Dakota. Minimal leaching and denitrification due to a relatively dry climate has helped make this test a good predictor of nitrogen fertilizer needs. The test and nitrogen recommendation system is based on a two foot deep soil sample and a calibrated nitrogen requirement for common crops grown in South Dakota (Table 1). Extensive field plot data shows that the two foot deep... |
94. The Science Behind NutrientStarNutrientStar is a science-based assessment and education program that is focused on products and tools that are marketed to increase nitrogen use efficiency. The program was initiated about three years ago by the Environmental Defense Fund with a primary focus on corn production in the Mississippi River Basin. NutrientStar operates with support from a panel of ten soil scientists plus administrative consultant staff. Panel activities include developing recommended protocol... J. Schepers |
95. The State of the Art StartersInterest in reduced tillage has caused a resurgence in the use of starter fertilizer. Starter fertilizer research has been conducted on many crops across the country. The purpose of this paper is to highlight recent research on a variety of crops including corn. cotton, sorghum, soybean, canola, sugar beet, and potato. Increased yields from starter fertilizers are common in low P soils and several factors may lead to increased yields even when soil P and K levels are high. Geographic trends in y... |
96. Trapping Function of Grassed FiltersThe potential to contaminate rivers, streams, and other natural water bodies with sediment, nutrients, pesticides and bacteria in runoff from agricultural land is a very important water quality issue. Conservation tillage has proven to be effective in decreasing soil exposure to rainfall, thus decreasing water runoff and erosion potential. Vegetative filters slow down runoff that allows sediment, nutrients, pesticides and bacteria to be deposited. Combining conservation tillage with vegetative f... |
97. Update on the Certified Crop Adviser-CCA-ProgramThe Certified Crop Adviser (CCA) program implemented by the American Society of Agronomy (ASA) and the American Registry for Certified Professionals in Agronomy, Crops; and Soils (ARCPACS) through the cooperation of various state and regional boards will soon begin its second year. To date approximately 2100 people have taken the state and/or national exams and are in the process of completing the other requirements for certification. Several new state or multi-state CCA Boards have been organiz... |
98. Use of A Wheat Cover Crop to Trap Residual Soil N for No-till CornIn continued work on long-term no-till plots, wheat was tested as a winter cover crop to determine how much carryover soil N it would accumulate from the preceding no-till corn crop and make available to the successive no-till corn crop. Wheat biomass at time of planting no-till corn was about 1.7 times greater following 240 lbs N/A on the preceding corn than following 80 lbs N/A. However, maximum wheat biomass was only about 1 T/A, and contained only 15 lbs N/A more than wheat grown following c... |
99. Using High-Tech Media Tools to Transfer the Principals of System Research to FarmersBeginning in 1981, research and extension personnel at Virginia Tech and the University of Maryland formed Intensive Wheat Management Teams. Over the next six years these Teams developed a higher yielding, more profitable and environmentally superior soft red winter wheat production system. Yields greater than 100 bu/a were achieved every year. This was at a time when average wheat yields were in the 40 bu/a range (Table 1). Intensive wheat research continues today to refine and update the syste... |
100. Variable-Rate Fertilizer Application- Update and EconomicsThe potential for application of computer-controlled, satellite-guided, variable-rate application systems for fertilizer has opened an interesting new area of research and development. While variable-rate application is not new--and does not require the com- puter or satellite systems to be useful--the technology is definitely helping to convince dealers and farmers that this concept has broader potential. Economic pressures and environmental concerns are leading them to take a closer look at ho... |
101. What Grid Cell Size is Best for P and K Soil Testing in MinnesotaA study to evaluate the best grid cell size and best soil san~ple system for immobile nutrients was conducted in South-Central Minnesota from 1993 to 1995. A corn/soybean cropping system was used. The soils at the research sites were formed in glacial till. Three grid cell sizes, 60 x 60 ft., 180 x 180 ft., and 300 x 300 ft. were evaluated. The sampling patterns included a mid-plot sample, a 60 x 60 ft. grid all-point pattern. and five to nine sample pattern. The smaller the grid cell the better... |