Soil health benefits of cover crops and forages systems

Authors: Acosta-Martinez, Veronica; WEST, CHARLES - Texas Tech University

Submitted to: Meeting Abstract
Publication Type: Abstract Only
Publication Acceptance Date: 9/3/2020
Publication Date: 9/3/2020
Citation: Acosta Martinez, V., West, C. 2020. Soil health benefits of cover crops and forages systems. Meeting Abstract. 1.

Interpretive Summary:

Technical Abstract: The Texas Alliance for Water Conservation (TAWC) is an outreach project at Texas Tech University that has collaborated with local producers since 2005 to conserve groundwater in the Southern High Plains region. The TAWC demonstrates on-farm strategies of irrigation and crop production that sustain profitability through improving soil health, irrigation scheduling, efficient irrigation delivery, and integrating livestock and cropping systems. Our team has been conducting soil health assessments in this region over two decades to link the biological component to organic matter dynamics and biogeochemical cycling. The influence of different forages has been evaluated to define integrated crop-livestock systems that enhance water conservation and sustainability as producers transition to low irrigation and dryland management. The water supply for irrigation from the Ogallala aquifer is diminishing because of its low recharge rate, which has worsened as droughts and heat waves become more frequent (e.g., 2011 and 2016). As a consequence, the search for drought-tolerant forages, crops, and management strategies is critical. The focus on soil health provides information on the below-ground interactions of management, soil, and climate that explain how microbial populations, enzyme activities, and organic matter pools relate to soil conditions that favor water retention and plant growth. These findings are extended to area producers through the TAWC presentations at field days and webinars. Previous work demonstrated a linkage between increased soil microbial community size and multiple ecological benefits in a novel integrated crop-livestock system customized for this region [perennial pasture comprising old world bluestem (OWB) and a wheat-fallow-rye-cotton rotation in contrast to 100% land area in continuous cotton]. The novel system required 36% less fertilizer and 25% less irrigation water while being as profitable as placing all land under continuous cotton over 10 years. Reduced tillage and increased vegetation inputs under OWB resulted in 59% greater frequency of macroaggregates than under continuous cotton. Soil organic carbon (SOC) continued to increase by 22% in the integrated system 13 yr. Other efforts showed that OWB deters soil-dwelling fire ants and harvester ants, which are deleterious to cattle health and forage persistence. Subsequent work included OWB growing with alfalfa, which showed further enhancements in SOC, soil microbial diversity, and biogeochemical cycling than OWB without alfalfa. Integrating the N2-fixing alfalfa with OWB eliminated the annual practice of applying 67 kg N ha-1 of fertilizer nitrogen (annually saving ~$50 ha-1) and increased soil N accretion and cycling over grass-alone. The effects of cover crops and reduced tillage are also being considered for integrated crop-livestock systems owing to their multiple benefits to decrease soil surface temperature, reduce evaporative losses of soil water, increase biomass production, and reduce wind erosion through better soil cover. This presentation will provide an overview of soil health, the response of different biological indicators to different forages, and provide additional considerations needed to modify integrated crop-livestock systems in this region in addition to soil health.