5 resultados para fertilizer N application rate
em Digital Repository at Iowa State University
Resumo:
Historically, sulfur (S) application has not been recommended on Iowa soils for corn and soybean production. Soils supply, or a combination from sources such as soil organic matter, profile sulfate, manure, and precipitation have met crop S needs. However, over the past few years, S deficiencies in alfalfa and corn have been documented. Large crop yield responses have been measured in some fields containing soils with low organic matter, side-slope landscape position, or coarse soil texture, especially in northeastern Iowa. The objective of this study was to determine S response in corn and soybean in north-central Iowa.
Resumo:
Producers utilizing a two year rotation of corn and soybean often apply fertilizer on a biannual basis, spreading recommended amounts of phosphorus and potassium for both crops prior to corn establishment. This approach minimizes application costs and is in accordance with university fertility recommendations that have found a low probability of fertilizer yield response when soils tested at the medium/optimum level or above. However, the field trials on which these state recommendations were developed are often several decades old. Increases in average corn and soybean yields and associated increases in crop nutrient removal rates have called into question the validity of these recommendations for current production environments. This study investigated the response of soil test levels and grain yield to annual and biannual fertilizer applications made at 1x and 2x rates of current university fertilizer recommendations.
Resumo:
During the past five years we have developed three emission calorimeters (EC) that can be used to evaluate mass generation and utilization of gasses. We have tested various treatments that significantly reduced ammonia generation by laying hen manure (Harrison and Koelkebeck, 2002; 2003).
Resumo:
Swine manure and fertilizer can be used to supply the nitrogen (N) and phosphorus (P) needs of crops. Excess P application sometimes applied with N-based manure for corn increases the risk of P loss and water quality impairment. Poor water quality in Iowa streams and lakes due to excess P has prompted questions about the impact of cropping and nutrient management systems on P loss from fields.
Resumo:
The primary objective of this project was to determine the impact of appropriate rates of swine manure applications to corn and soybeans based on nitrogen and phosphorus requirements of crops, soil phosphorus accumulation, and the potential of nitrate and phosphorus leaching to groundwater. Another purpose of this long-term experimental study was to develop and recommend appropriate manure and nutrient management practices to producers to minimize the water contamination potential and enhance the use of swine manure as inorganic fertilizer. A third component of this study was to determine the potential effects of rye as a cover crop to reduce nitrate loss to shallow ground water.