Soil health influenced more by conservation management than irrigation in semi-arid cotton (gossypium hirsutum) systems grown in sandy loam soils

Authors: PETERMANN, BILLI - Texas Tech University; LEWIS, KATIE - Texas Tech University; Acosta-Martinez, Veronica; LAZA, HAYDEE - Texas Tech University; STEFFAN, JOSHUA - Dickinson State University; SLAUGHTER, LINDSEY - Texas Tech University

Submitted to: Soil Science Society of America Journal
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 6/25/2024
Publication Date: N/A
Citation: N/A

Interpretive Summary: The Texas Southern High Plains (SHP) region has generally produced cotton under intensive tillage operations, and using as much irrigation as possible to compensate for less than optimal precipitation. However, frequent droughts and extremely hot summers are reducing groundwater for irrigation, and our future depends on alternative management such as cover crops, crop rotations, and conservation tillage to improve soil health and water storage for future generations. Evaluating soil microbes can provide information on soil health as they are key to many functions that influence plant productivity, such as nutrient cycling, improved soil structure, and subsequent water dynamics. In this study, scientists from Texas Tech University, Texas A&M AgriLife, North Dakota Parks and Recreation and USDA-ARS took soil samples from two depths (0-10 cm, 10-20 cm) and the root zone for two years under different irrigation levels from a fine sandy loam under three long-term (> 10 years) cotton management systems: 1) conventionally tilled cotton, 2) reduced tilled cotton grown with a rye cover crop, and 3) a reduced tilled cotton and wheat rotation. Our results revealed that reducing tillage and growing cotton with a crop that reduce winter fallow periods can improve soil microbial communities and enzymes of nutrient cycling regardless of irrigation level in a sandy soil in this semi-arid region. These results suggested that alternative cropping practices that promote soil health can be developed for the Texas SHP.

Technical Abstract: Agricultural producers in semi-arid regions face many challenges while attempting to increase soil health and profitability, particularly climatic extremes and severe water and nutrient scarcity. Cropping production systems have historically relied on continuous cropping and irrigation to sustain productivity, but declining groundwater resources in these regions have prompted a greater focus on conservation practices such as cover crops, crop rotations, and conservation tillage to improve soil health and water storage. Our study aimed to compare soil physical, chemical, and microbial responses from two depths (0-10 cm, 10-20 cm) and the root zone from three long-term (> 7 years) semi-arid, sandy loam, cotton management strategies, each under high and low irrigation in a typical agroecosystem (Continuous monocrop with conventional tillage, CCCT) compared to two conservation systems that included a no-till with rye cover crop (NTCR) and a no-till with a cotton/wheat rotation (NTCW) for two years. Our results revealed management-induced differences in soil microbial communities and other soil health indicators regardless of irrigation level. The conservation systems had greater total FAME markers as indicators of soil microbial community size and soil organic matter (SOM) than the CCCT system. Furthermore, the NTCW maintained greater AMF biomass than the conventional practices. In addition, higher enzyme activities involved in C-N and P cycling were detected under conservation systems. Overall, our study suggests that conservation practices such as reduced tillage and diversified planting can improve soil biological health in sandy loam soils in this semi-arid region regardless of irrigation.