Agricultural Water Management (Nov 2023)
Landscape position and cover crops affects crop yields in a terrace-tiled field
Abstract
Cover crops (CC) provide soil ecosystem benefits including reduced soil erosion, improved soil health, and nutrient cycling. However, the effect of CCs on rotational commodity crop grain yields and nutrient uptake may vary at different landscape positions and under different soil moisture dynamics. The objectives of this study were to determine the influence of CCs in a terraced field on soil moisture at crop emergence and reproductive stages of corn (Zea mays L) and soybean (Glycine max L. Merr.) development, and evaluate CCmix (wheat (Triticum aestivum L.), radish (Raphanus raphanistrum subsp. Sativus), and turnip (Brassica rapa subsp. Rapa)) and cereal rye (Secale cereale L.) effect on corn and soybean grain yield and plant nutrient concentration, respectively. A randomized complete block design with two treatments including cover crop (CC) and no cover crop (no CC) and three replications was used. In this 4-year study, cereal rye produced 1.0–1.6 Mg ha−1 higher aboveground biomass compared to the CCmix species. Nutrient uptake in the CCmix biomass was greater than cereal rye. Soybean yield following cereal rye termination was not influenced by the CC treatment (P = 0.3229). Dry climatic conditions during the soybean growing period and landscape positions influenced grain yield and nutrient uptake. Average soybean yield at different landscape positions was ranked as shoulder (4.8 Mg ha−1) > backslope (4.4 Mg ha−1) > footslope (3.9 Mg ha−1) > channel (3.6 Mg ha−1). In 2021, corn yield was reduced 29% following the CCmix compared to no CC control, indicating a yield penalty when corn was preceded with the CCmix species. In this study, higher CC biomass production exacerbated soil wetness in a wet year (2021), resulting in uneven corn germination and excess soil water stress on plant growth. Increased soil wetness at channel and footslope positions in 2019 and 2021 reduced corn yield 45–70%. This study suggests that CCs in terraced fields can have a neutral or negative effect on the following commodity crop yield depending on the weather conditions.
