Michigan Precision Agriculture Research – NCR-180 is a committee of researchers from land grant university experiment stations who are working in precision agriculture. Committee members prepare annual research summaries, which are presented and discussed at a meeting in January. Below are abstracts of Michigan research presented to the group in January. Research reports for Michigan and other states can be found at: http://precision.agri.umn.edu/ncr180_Pawg/research/research.html

Comparative Analysis of Site-Specific and Conventional Fertility Management for Corn and Soybeans Grown in Michigan - Neil Miller, D.D. Warncke, R.C. Brook

This a one of several projects managed by the Phosphate and Potash Institute. The project objective is to evaluate the value and utility of precision agriculture soil fertility management practices, systems and concepts in the production of soybeans and corn under Michigan growing conditions. Specifically, variable rate application of phosphorous, potassium and lime are compared with whole field application. Two cooperating farmers in eastern Michigan have each donated the use of two 40 acre fields, one planted to corn and one to soybeans. Digital elevation maps of each of the four fields have been made. Soil electrical conductivity analysis has been performed using both the EM38 and the Veris technologies. An order 1 soil survey is being prepared by NRCS. Corn tissue samples were pulled at tasseling and soybean tissue samples in August for soybeans. EMERGE aerial photographs were obtained for three of the four sites in 1998 and for all four sites in 1999. Combine yield monitor data was taken for each of the fields. A large number of data set are being collected during this project. Yield, and a derived data set called gross margin, are the primary dependent variables being considered. Other data sets have been included as a way to help understand the effect of variability of field characteristics and/or production practices and environment, on the dependent variables.

Accuracy of Soil Sampling Methods and Implications for Fertility Management and Crop Production in Michigan - Neil Miller, Roger Brook, and Scott Swinton

Soil fertility sampling methods were compared on 10 commercial farm fields in 1999. Independent samples were taken in each field using 2.5 acre grid point sampling (GS), 2.5 acre "smart" (directed) point sampling (SS), and 5-10 acre management zone (ZS) approaches. The accuracy of interpolated values was compared at independent sample points taken from each field at the same time but at different locations. Sample method accuracy varied from field to field, but SS and ZS sampling outperformed GS sampling overall. Sampling accuracy also varied widely depending on the fertility element being measured, with pH, phosphorus and organic matter showing a consistently greater spatial structure than potassium and nitrate.

A project management team has been assembled for to evaluate the value and utility (based on practices that are highly productive, economically viable and environmentally benign) of precision agriculture practices, systems and concepts in the production of chipping potatoes produced under Michigan growing conditions. The project will involves field scale evaluation of spatial and temporal distributions of fertility, pests and tuber quality (yield, size distribution, cumulative defects) and small plot studies to document the effects of adjusting system inputs parameters on tuber quality. Field research sites were established in Montcalm and St. Joseph Co. The Montcalm site had a calcium / fumigation study overlayed for the purpose of studying calcium related quality issues. The St. Joseph site is in a 3-year potato-seed corn-seed corn rotation, with approximately 1/3 of the field in potatoes each year. Variability of fertility levels within the St. Joseph Co. field appear to be more closely correlated to historical field boundaries than to cropping practices or fertilizer applications within the past 15 years.

Roger Brook