Start Date

18-11-1998 12:00 AM

Description

Soil fertility management can be greatly improved with the use of precision agriculture technologies. Differential global positioning systems (DGPS), yield monitors, aerial photographs, and variable rate technology can improve both soil fertility evaluation and fertilizer or lime application. Soil sampling in the field is the most important source of error in soil testing. A very small amount of soil needs to appropriately represent thousands of tons of soil and usually there is large spatial variability of nutrients. Intensive soil sampling and variable-rate fertilization can improve the efficacy of fertilization and liming compared with the conventional practice of collecting soil samples from large areas and using single-rate fertilizer applications. Although variable-rate fertilization can be used on the basis of the traditional sampling of areas identified on the basis of soil types, landscape, or previous management, many believe that it should be based on intensive grid sampling. Conventional soil sampling may not be appropriate for precision agriculture because one composite sample, even if it is collected from one soil mapping unit, may not adequately represent apparently uniform areas with long histories of cropping and fertilization. This presentation discusses the advantages and disadvantages of various soil sampling methods and summarizes ongoing research on the spatial variability of phosphorus (P) and potassium (K) and the cost-effectiveness of variable-rate fertilization or liming for corn and soybean crops.

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Nov 18th, 12:00 AM

Soil Sampling Strategies for Variable Rate P and K Fertilization and Liming

Soil fertility management can be greatly improved with the use of precision agriculture technologies. Differential global positioning systems (DGPS), yield monitors, aerial photographs, and variable rate technology can improve both soil fertility evaluation and fertilizer or lime application. Soil sampling in the field is the most important source of error in soil testing. A very small amount of soil needs to appropriately represent thousands of tons of soil and usually there is large spatial variability of nutrients. Intensive soil sampling and variable-rate fertilization can improve the efficacy of fertilization and liming compared with the conventional practice of collecting soil samples from large areas and using single-rate fertilizer applications. Although variable-rate fertilization can be used on the basis of the traditional sampling of areas identified on the basis of soil types, landscape, or previous management, many believe that it should be based on intensive grid sampling. Conventional soil sampling may not be appropriate for precision agriculture because one composite sample, even if it is collected from one soil mapping unit, may not adequately represent apparently uniform areas with long histories of cropping and fertilization. This presentation discusses the advantages and disadvantages of various soil sampling methods and summarizes ongoing research on the spatial variability of phosphorus (P) and potassium (K) and the cost-effectiveness of variable-rate fertilization or liming for corn and soybean crops.