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9633. Hanson, L.D., M. Warner, J.R. Schafer and E. Vasey. 1989. Automating field operations for variable conditions.. Agronomy Abstracts, p. 316. Amer. Soc. Agron., Madison, WI..
Our objective is to tailor fertilizer and other chemical applications to variable field conditions in a practical, cost effective system. Auhtors have been working with soil management PC software for several years. In 1988 a new program was prepared to run in real time on a laptop computer on board a field sprayer to record post emergence spot sprayed areas in sugar beets. Field location control came by interfacing a distance measuring device with the computer. The lateral dimension location was fixed by implement width and pass number. The prototype system was a combination of a wheel revolution counter, a SHARP4502 laptop computer and a program named "weed tracker". The data file created in the mapping phase of the operation can be used later to automatically spray or control other operation in the same field. The developers of the system are working with a Minnesota electronics manufacturer to market a commercial version of the prototype.
10070. Mahler, R.. undated. Catena management in northern Idaho.. unpublished handout for Extension agent training.
In northern Idaho, water is often not limiting to crop production. Also, nutrient use efficiency is lower than in drier areas. Where annual precipitation is <17", fall application of all N fertilizer is best. But as rainfall increases, nutrient use efficiency can be increased by applying a greater share of N in the spring. Fertility experiments have shown that growers are probably underfertilizing bottomland positions and overfertilizing slopes for maximum net return from fertilizer. Several questions need to be answered to help improve nutrient efficiency. Is the value 2.7 lb N/bu wheat linear? Research results indicate that only 2.4 lb N/bu is needed at 80-90% of maximum yield. Is residual N used as efficienctly by plants from surface layers versus subsurface layers? What is the best approach to estimating N mineralization rates in a soil? Rates in northern Idaho can vary as much as 100% depending on weather conditions.