Soil Mapping for Fine-Tuned Nutrient Management By MATT COMREY | Technical Nutrition Agronomist, Wilbur-Ellis Agribusiness, WRCCA Board of Directors
Figure 1. Soil mapping coupled with a variable rate (VR) fertilizer application aims to maximize one of the 4 Rs: Right Rate (all photos courtesy M. Comrey.)
T
his year will likely prove as challenging a year as any from recent past due to supply chain disruptions, commodity pricing and drought here in the Central Valley. Growers who can weather this year’s uncertainty will be poised for success in the future due to an increased focus on efficiency and proper input management. From proper sprayer calibration to increased awareness of nutrient use efficiency, the incentive for improving input efficiency is particularly strong as the supply of inputs remains questionable at best. Product placement when completing a fertilizer application is vital, particularly when deploying dry fertilizers in a
20
Progressive Crop Consultant
Figure 2. Soil Optix soil sensing tool helps map variability in the soil.
band and/or broadcast. The low solubility of many of the common dry fertilizers used up and down the state means nutrient release is slow and nutrient movement through the soil complex is low. This is particularly problematic for potassium- and phosphate-based fertilizers whose primary method of uptake is via diffusion. The 4 Rs of Nutrient Stewardship are helpful in guiding growers through the considerations associated with properly applying nutrients: Right Source, Right Place, Right Form and Right Rate. Turbulent times and uncertainty bring opportunities for growers to leverage new technologies in their ongoing pursuit to maximize efficiency.
March / April 2022
Using GPS and soil mapping technology isn’t a new strategy for soil nutrient management but has gotten more and more attention in the past few years due to rapidly increasing fertilizer costs. Soil mapping coupled with a variable rate (VR) fertilizer application aims to maximize one of the 4 Rs: Right Rate by directly matching the fertilizer application rate with measured soil nutrient levels. This technology can effectively break a field or block into smaller management zones so different areas of the field ca n be treated differently. While this article highlights the use of GPS soil mapping as a tool
Continued on Page 22