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February, 2000
ON THE ROAD TO PRECISION AGRICULTURE
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
Intervention N and Irrigation Management Strategies for Corn. - F.J. Pierce and M. Elwadie.
This project, funded by the Corn Marketing Program of Michigan, will determine if corn managed with variable rate N fertilizer based on plant chlorophyll content and variable irrigation based on remotely sensed plant stress are more or less efficient then current fertilizer and irrigation practices. Specific objectives include (i) comparing prescription (at planting) and PSNT (Pre-sidedressed N test) based N management strategies with intervention N management strategies based on N stress in plants determined from chlorophyll measurements and (ii) comparing irrigation strategies based on need and scheduling with irrigation based on remote sensing spectral indices indicative of water stress in corn. Two field studies were conducted in 1999, one at the Kellogg Biological Station (KBS) and the other at the MSU campus research farm. At KBS, four N treatments were evaluated under no irrigation, MSU irrigation scheduling, and a sensor based irrigation regime. Irrigation water was applied using a trickle irrigation system. N treatments included no N applied, N applied at planting, N applied based on a PSNT test, and N applied when leaf chlorophyll indicated an N deficiency in corn. At MSU, N management strategies were evaluated under rainfed conditions and included the N treatments at KBS plus three additional N treatments including N applied based on Iowa State University’s PSNT recommendations, N applied when leaf chlorophyll indicated an N deficiency in corn using 90 Lbs of N with no further applications, and N applied at planting and any time N deficiency in corn was detected via the leaf chlorophyll content. At KBS, PSNT and sensor based N strategies applied less fertilizer N with no loss in corn yield with or without irrigation. At MSU, yields were lower in treatments where N applications were delayed because of dry soil conditions after N appl. The experiment will be repeated in 2000.
Site Specific Management of Nitrogen. - Natalie Rector, Neil Miller, Innovative Farmers of SC Michigan.
The goal of the project is to determine what data is important for determining variable rates of N; if variable rates of N are profitable; and if variable rates of N can decrease total N for corn production, thus leaving less potential N to reach the groundwater in our sandy loam area of Michigan. Twenty on-farm research plots have been implemented to test both the spatial relationship of flat rates of N across field situations and variable rates of N. These are randomized and replicated plots that encompass field size situations. They are located on five different farms, two fields per farm and two trials per field (flat rate and variable rate). Electrical conductivity measurements and elevation data have been used to define field management zones. The fields were then soil sampled utilizing these zones to help define areas. One infrared imagery fly over was taken of each field in August. Several N strategies have been implemented: 1) whole field management based on yield goals with one N rate; 2) site specific management based on yield goals with a variable rate of N applied based on a variable yield goal and past yield performance; 3)site specific management of variable rates of N based on PSNT soil tests; 4) site specific management using variable N rates based on yield goal potential and PSNT. All of the variable rate plots were sidedressed with 28% by one custom applicator. Yields were collected with the farmer's combine/yield monitor system in the fall of 1999. These plots are planned to be repeated for a total of three years.
Roger Brook
