As the tractor rolls across the ground, some machines will create maps of differences in soil moisture, compaction and fertility. This map will then be compared to another map of differences in yield within the field to create recommendations for maximizing the harvest.
Combines and some other harvesting equipment have "load monitors" on board, which record differences in yields within the field. This system also is connected to the GPS so the exact locations of yield information can be connected to specific sites. Along with the "yield map," information about the soil is being collected by sensors that reveal the moisture and nutrient status of the soil. Armed with this information, researchers are attempting to compare the yield maps to the "data maps" to determine what factors presumably have the greatest impact on yield.
Some differences in yield are due to differences in soil fertility and this also is correlated to soil type in some cases. With this information and the state-of-the- art application equipment, the farmer can apply fertilizer based on need, i.e. more can be applied in weak areas and less applied where the concentration is adequate.
The long-range goal of this research at the University of California, Davis campus is to apply site-specific amounts of fertilizer based on soil texture and soil fertility levels. Each site is equivalent to a "zone" depending on the gradient of the samples.
Most recent research is indicating that a greater difference in yield could be due to a moisture related problem, which is more related to the physical characteristics of the soil. Soil compaction also is being investigated as a reason for limiting growth and water consumption by the crop. Drip-system orifices could be tailored to the water needs of a particular field in relation to the soil texture map. More water could be delivered to the lighter soils and less to the heavier soils.
>> Herman Meister is the field crops agronomy adviser at the University of California-Imperial County Cooperative Extension.
>> The Cooperative Extension serves all residents of the Imperial Valley.