Assessing the Effectiveness of Individual Versus Multiple Nutrient Reduction Practices on Water Quality and Economic Viability

Date: 
Aug 2019

Issue

The Iowa Nutrient Reduction Strategy includes approximately 20 individual nitrogen-loss reduction practices, but there is little understanding about how these practices interact to affect water quality and profitability. Do stacked practices have additive or synergistic effects on nutrient loss reduction? The answer is unknown. This knowledge gap is largely the result of cost limitations on the testing of multiple, stacked practices with conventional field experiments.

Objective

 effect of individual versus multiple/stacked nutrient loss reduction practices
What if scenario: effect of individual versus multiple/stacked nutrient loss reduction practices

This project will quantify the effectiveness of individual versus multiple/stacked nutrient loss reduction practices to identify suites of practices that minimize trade-offs between improvements to water quality and profitability. Data will be used from eight experimental locations across Iowa to train and test the Agricultural Production Systems Simulator, or APSIM, cropping systems model.

Recent modeling work from PI Archontoulis (Fig. 1) indicates that there is no a single (best) management practice that can increase productivity in Iowa. In contrast, small changes to multiple management factors have a synergistic effect and much greater chances of increasing corn and soybean yields. The team hypothesizes the same is true for water quality, and when the objective is dual (increase both profitability and water quality), that trade-offs will arise among practices.

Approach

Data from eight experimental locations across Iowa will be used to train and test the APSIM cropping systems model. Then, the power of modeling will be used to perform scenario analysis to quantify the impact of various practices.