Cover Crops Impacts on Louisiana Corn Production and Soil Properties

Abstract

Core Ideas Combination of cover crops with conservation tillage increased soil C. Cover crops significantly reduced nitrate‐N levels during the fallow season. Legume cover crops reduced N requirements when compared with non‐legumes. Conventionally managed, continuous monoculture row‐crop production has depleted the soil of nutrients, organic matter, and overall productivity. This has increased the need for external inputs, specifically N, to meet crop demand. Despite the growing interest in conservation practices, including minimal tillage and cover crops, little work has been reported in the Mid‐South region. Cereal rye (Secale cereal L.), forage radish (Raphanus sativus var. longipinnatus L.), berseem clover (Trifolium alexandrinum L.), crimson clover (Trifolium incarnatum L), winter pea (Pisium sativum L), hairy vetch (Vicia villosa Roth), and a cereal rye–forage radish mix were seeded in discrete blocks in October 2014, 2015, and 2016 along with a non‐cover fallow. Each block was divided into 16 sub‐plots to which one of four N fertilizer rates (0, 235, 268, and 302 kg N ha−1) were applied. Corn (Zea mays L.) grain yields increased with additions of N fertilizer; however, no difference was observed between the three fertilizer rates in 2 of 3 yr. Cover crops aided in the uptake and recycling of inorganic N, potentially reducing losses and providing N for subsequent cash crops. Following legume cover crops, corn grain yields were maximized with the addition of 235 kg N ha−1. Inclusion of grass and brassicas with no additional N input reduced corn grain yield, which remained lower than yield measured following legumes up to the 302 kg N ha−1 rate. Secondary benefits of cover crops included increased soil C (36%) and N (22%), and N cycling over a 2‐yr period.

Cover crop and minimum tillage effects on yield, irrigation water use, and net returns

“…Limited studies have been conducted in the mid-South to quantify the expected benefits of cover crop-minimal tillage systems, and even fewer have been conducted at field scale to elucidate how adopting this practice will fit within the cornsoybean rotational systems of this region. Region-specific results from recent investigations in smaller research plots have reported no change (and, in some instances, decreases) in corn and soybean yields after implementation of cover crops and reduction in tillage (Bryant et al, 2020;Patton, 2016;Sanchez et al, 2019 Reddy (2001Reddy ( , 2003 determined that the costs associated with planting cover crops in Mississippi soybean resulted in a net loss due to increased seed, planting, and termination costs, but these results may not be reflective of the current situation.…”

“…Yield response to adoption of cover crops in corn and soybean production systems has historically been variable. Some studies have shown that adding cover crops improved yield (Chalise et al., 2019; Chu et al., 2017; Miguez & Bollero, 2005), whereas others observed no difference in yield (Wortman et al., 2012), or even reduced yields (Reddy, 2001; Sanchez et al., 2019). Multiple authors have reviewed relevant research on cover crops to identify trends in yield response (Blanco‐Canqui et al., 2015; Daryanto et al., 2018; Marcillo & Miguez, 2017).…”

On-farm assessment of cover cropping effects on soil C and N pools, enzyme activities, and microbial community structure

“…These CCs produce relatively higher N content residue which can be easily broken down and made available for subsequent crops. The grass CCs with well-developed root system has strong nutrient-scavenging ability, especially for N, therefore, has been used to reduce N leaching (Kaspar et al , 2012; Sanchez et al , 2019a). Biomass from ryegrass CC can enhance soil organic matter and reduce N leaching during winter period and protects the bare soil from wind and water erosion even for the heavy rain during the early spring (Kaye et al , 2019; Salmerón et al , 2011).…”

Cover crop effects on infiltration, aggregate stability, and water retention in the Lower Mississippi River Valley

“…Identifying the specific improvements that CC can impart on the near-surface soil and hydrologic properties in the LMRV will allow producers to make informed decisions about utilizing CC to contribute to overall soil health and aquifer recharge in the LMRV region of eastern Arkansas. While few parameters in this study were significantly affected by CC treatment, some parameters, given more time and based on previous CC study results (Keisling et al, 1994;Sanchez et al, 2019;Steele et al, 2012;Villamil et al, 2006), would be expected to continue to deviate over time to the point where differences would eventually become significant (Blanco-Canqui & Ruis, 2020). However, the lack of significant differences between CC and NCC do not mean the soil, and ecosystem as a whole, is not benefitting from the presence of CC.…”

“…Additionally, TC content was at least 1.1 times greater in the top 15 cm and TC concentration was 1.3 times greater in the top 2 cm of a silt‐loam soil in west‐central Mississippi under 6 years of CC rotations (i.e., cotton‐clover and cotton‐rye) compared to NCC (Locke et al., 2012). Over the course of 2 years in a north‐eastern Louisiana conservation‐tillage corn production study, SOM in the top 10 cm increased from 21.9 to 25.2 g kg −1 , while TC concentration increased 1.4 times, under various CC (i.e., rye, radish ( Raphanus sativus ), berseem clover ( Trifolium alexandrinum ), crimson clover, winter pea, vetch, and rye‐radish mix) in a silt‐loam soil compared to NCC (Sanchez et al., 2019).…”