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ARS Home » Midwest Area » Columbia, Missouri » Cropping Systems and Water Quality Research » Research » Publications at this Location » Publication #319676

Title: Stewardship of water and fertilizer in irrigated cotton

item Vories, Earl - Earl
item JONES, ANDREA - University Of Missouri

Submitted to: University of Missouri Agricultural Experiment Station Publication
Publication Type: Abstract Only
Publication Acceptance Date: 8/5/2015
Publication Date: N/A
Citation: N/A

Interpretive Summary:

Technical Abstract: Agriculture is a vital part of the southeast Missouri economy and it is essential that we maintain our precious soil and water resources. While we have shallow, high quality groundwater for irrigation, it is important to realize that our aquifer, the Mississippi River Valley Alluvial Aquifer, also provides water for irrigation in Arkansas, Tennessee, Mississippi, and Louisiana. In some areas, years of pumping more than natural recharge can replace has led to serious shortages. Furthermore, runoff water from excess irrigation on fields can carry soil and nutrients that can cause offsite problems. Most of us have heard of the hypoxic zone in the Gulf of Mexico, where insufficient oxygen affects aquatic life during parts of the year, but we can also have problems much closer to home. Applying optimal amounts of water and fertilizer to our crops saves the farmer money and protects the environment for everyone. To better understand what the optimal amounts are, we calculate balances, where we know what is applied to the field and what leaves. To accomplish that, we took one of our fields at the Fisher Delta Research Center and divided it into six sub-fields of approximately one acre each. Each subfield is surrounded by levees so that runoff water cannot enter from another field and runoff from the sub-field leaves at a single point. By using a flowmeter to measure the irrigation water applied and the rainfall for Lee Farm on the Agricultural Electronic Bulletin Board (AgEBB), we have a precise knowledge of what was applied. We can estimate evaptranspiration and by placing a flume in the drain we can measure what leaves the field as runoff. We can sample the water and compare the nutrients in the runoff to our fertilizer applications. We have an accurate record of what was removed from the field in harvest and we can measure or estimate its water and nutrient content. This information will allow us to calculate the efficiencies of our applications and identify areas where improvement is needed. Currently we are comparing controlled release nitrogen to urea on cotton. We will monitor the field year round to determine both in-season and off-season losses. While suspended sediments in the runoff are not part of the current study, the measurement could be included in the future. This system can also be used to investigate cover crops, no-till production, soil erosion, greenhouse gas emission, and an almost limitless number of practices for cotton or other crops. The key is closely measuring what is added to the field and what is removed and determining what contributed to the differences. This information will help to insure that our farming practices are sustainable and we continue to produce food and fiber in an economical and environmentally sound way.