New technologies such as differential global positioning systems (DGPS) and geographical information systems (GIS) are making it possible to manage variability in soil properties and the microenvironment within a field. By providing information about where variability occurs and the patterns that exist in crop and soil properties, DGPS and GIS technologies have the potential of improving crop management practices. Yield monitoring systems linked to DGPS receivers are available for several types of horticultural crops and can be used in variety selection and/or improving crop management. Precision soil sampling and remote sensing technologies can be used to scout for infestations of insects, diseases, or weeds, to determine the distribution of soil nutrients, and to monitor produce quality by measuring crop vigor. Combined with variable rate application systems, precision soil sampling and remote sensing can help direct fertilizer, herbicide, pesticide, and/or fungicide applications to only those regions of the field that require soil amendments or are above threshold levels. This could result in less chemical use and improved crop performance. As with any information driven system, the data must be accurate, inexpensive to collect, and, most importantly, must become part of a decision process that results in improvements in crop yield, productivity, and/or environmental stewardship.
Carl R. Crozier, Ronnie W. Heiniger, and Michael Bishop
During Summer 1997, soil compaction in agricultural fields was evaluated using a portable electronic cone penetrometer. Rather than requiring the operator to read from an analog scale, this penetrometer stores data in a digital form, which are downloaded to a personal computer for analysis. Soil strength, measured in 1-inch (2.5-cm) increments, can be stored for up to 100 25-inch (64-cm) deep soil profiles. This instrument can be operated by a single person and facilitates collecting large data sets required to characterize highly variable soil environments. Because the penetrometer was designed to measure and formulate predictions about the trafficability of wet soils, it is often incapable of measuring the higher soil resistance occurring in drier agricultural fields. If used soon after rainfall or irrigation, it is useful in detecting hardpans associated with tillage or traffic patterns.