Drainage water management practices affect water quality, soil properties, and crop production
Authors:   , Kaur Harpreet 
Published: October 2023

Several agricultural management practices such as terrace construction, cover crops (CC), drainage water recycling (DWR), free drainage (FD), and 4R nitrogen (N) management can influence water quality, soil properties, and crop production. This dissertation includes results from four studies conducted at the MU Greenley Research Center, Grace Greeley farm, and Ross Jones farm. Long-term, no-till research evaluated the influence of a wheat (Triticum aestivum L.), radish (Raphanus raphanistrum subsp. Sativus), and turnip (Brassica rapa subsp. Rapa) cover crop mix (3xCCmix) aerial seeded into soybean (Glycine max L.) and cereal rye (Secale cereale) drill seeded following corn (Zea mays L.) on soil properties, water quality, and grain yield. This study (i) assessed nutrient loss in surface runoff with CC during the cover and commodity crop season; (ii) determined the effect of variable spring precipitation, soil conditions, and the impact of cover crops on fertilizer loss following phosphorus application; (iii) quantified the effect of cover crops and landscape position on soil health parameters in a tile-terraced no-till field; and (iv) evaluated the effect of landscape position and soil moisture on CC establishment, commodity crop production and nutrient removal in a no-till, terrace-tiled field with and without CCs. Runoff water samples were collected using automated water samplers from individual runoff flumes and analyzed for total suspended solids (TSS), nitrate-N (NO3-N), dissolved reactive phosphorus (PO4-P), and total phosphorus (TP). The nutrient loss in surface runoff was evaluated for each season separately over years. Averaged over two years, 16 percent and 12 percent less runoff discharge was observed with the 3xCCmix and cereal rye CC treatment, respectively, compared to no CC. The TSS load was 50 percent lower following the aerially seeded 3xCCmix compared to no CC, while drill seeding cereal rye had no significant effect on sediment loss. The CC plants and residue reduced NO3-N loads in surface runoff 20 percent, 54 percent, and 68 percent during the corn, cereal rye, and soybean seasons, respectively, due to CC N uptake and reduced water flow with the CCs. Variable spring precipitation and soil conditions affected the impact of CCs on P fertilizer loss following a spring phosphorus (P) application. Soil samples from each landscape position in the terraced field were collected at a 0-15 cm soil depth before P fertilizer application and after CC termination. Soil moisture at different landscape positions was evaluated at 0-5 cm depth using Watermark (Irrometer, Riverside, CA) sensors. Runoff water samples between the P fertilizer application until CC termination were evaluated for TSS, TP, and PO4-P. Cover crop biomass P uptake was determined at the time of CC termination. The CCs had an inconsistent effect on TP and PO4-P concentration and load which was affected by variable spring precipitation, soil moisture, and temperature. There was no effect of the CCs on TP and PO4-P in 2019 and 2021 with 3xCCmix. Cereal rye reduced TP and PO4-P load 70 percent and 73 percent respectively, compared to no CC. The variation in soil moisture, temperature, and net precipitation during observation period over years affected available soil P pools due to differences in CC species P uptake, growth before termination, residue decomposition, and P loss in surface runoff water. Overall, cereal rye had greater P uptake compared to the 3xCCmix species which also reduced P loss in water and greater differences in soil P status compared to no CC. P loss to frozen soils in the spring had 29 percent of applied P loss in the presence of a CC and 37 percent loss in the absence of a CC.