Site‐specific effects of winter cover crops on soil water storage

Abstract

Addition of an overwintering cereal rye (Secale cereale L.) cover crop (CC) to midwestern maize (Zea mays L.)-based systems offers several environmental benefits, but the long-term effects of this practice on soil hydrological properties are not well understood. We utilized four long-term (10+ yr) trials (two commercial fields, two research plots) in Iowa that included a replicated winter rye CC and no-cover treatment in no-till maize/soybean [Glycine max (L.) Merr.] systems. We took intact 7.62cm diam. soil samples from a 10-to-18-cm depth shortly after cash crop planting in the spring. We measured the soil water retention curve using matric potentials ranging from saturation to -500 cmH 2 O. In addition, we measured organic matter, textural composition, and bulk densities of the soil samples. At the depth sampled, CCs did not meaningfully affect bulk density, water contents at saturation, or air-entry potentials at any trial, nor increase the percentage of macropores. At two trials, soil water content at field capacity (-100 cmH 2 O) in the CC treatments was 2.5 vol% (SE: 1.2%; commercial field) and 2.4 vol% (SE: 1.3%; research plot) higher compared with the no-cover treatments. This increase could meaningfully reduce the amount of water drained from a field after a saturating rain and should be considered when assessing CC impacts on landscape hydrology. The presence or absence of a CC effect on field capacity was not related to CC aboveground biomass production, previous cash crop, or soil texture at the trial sites. Based on our results, a causal model, and previous literature we hypothesize CC root characteristics are key to understanding variable effects of CCs on soil water storage. Our results indicate it is possible for CCs to meaningfully affect soil water storage, but more research is needed on the mechanisms by which these changes occur. INTRODUCTIONAddition of an overwintering cereal rye (Secale cereale L.) cover crop (CC) to midwestern maize (Zea mays L.)based systems potentially offers several environmental benefits including reduced soil erosion and nutrient pollution Abbreviations: CC, cover crop.This is an open access article under the terms of the Creative Commons Attribution License, which permits use, distribution and reproduction in any medium, provided the original work is properly cited.

Cover Crop Composition in Long-Term No-Till Soils in Semi-Arid Environments Do Not Influence Soil Health Measurements

“…Evidence of this occurs as studies ranging from 9 to 15 years in Iowa, California, and the Netherlands determined that inclusion of cover crops improved soil organic matter and other biological properties (N mineralization, microbial abundance and diversity, fungi:bacteria ratio) (Martínez-García et al, 2018;Moore et al, 2014;Schmidt et al, 2018). Other long-term studies in Kansas, Iowa, Illinois, and Spain (>10 yr) found including cover crops improved various soil physical properties including soil organic C, soil aggregation, mean weight diameter of dry aggregates, bulk density, or infiltration (Blanco-Canqui et al, 2011;Blanco-Canqui & Jasa, 2019;Gabriel et al, 2021;Nichols et al, 2022;Olson et al, 2014).…”

“…Norris et al, 2018), and barley (Hordeum vulgare) enhanced soil respiration (Sanz-Cobena et al, 2014). The different effects of these broadleaf and grass cover crops on soil properties is hypothesized to be related to root type and structure (Blanco-Canqui & Ruis, 2020;Nichols et al, 2022). Legumes and grasses have extensive fibrous root systems interacting with large volumes of soil, while brassicas generally have tap roots (tuber forming species) that interact will lower volumes of soil.…”

Cover crop composition in long‐term no‐till soils in semi‐arid environments do not influence soil health measurements after one year

“…Norris et al, 2018), and barley (Hordeum vulgare L.) enhanced soil respiration (Sanz-Cobena et al, 2014). The different effects of these broadleaf and grass cover crops on soil properties are hypothesized to be related to root type and structure Nichols et al, 2022). Legumes with extensive tap roots and secondary lateral roots and grasses with extensive fibrous root systems interact with large volumes of soil, compared to brassicas that have a larger tap root with few laterals (tuber-forming species) and interact with lower volumes of soil.…”

“…Several studies have compared the effect of including a cover crop against no cover crop, and it was found that radishes ( Raphanus sativus L.) increased permanganate oxidizable carbon (POXC; Wang et al., 2017), rape ( Brassica napus L.) increased soil respiration rates (Sanz‐Cobena et al., 2014), cereal rye ( Secale cereale L.) increased particulate organic matter (OM) and potentially mineralizable nitrogen (PMN; Moore et al., 2014; R. Norris et al., 2018), and barley ( Hordeum vulgare L.) enhanced soil respiration (Sanz‐Cobena et al., 2014). The different effects of these broadleaf and grass cover crops on soil properties are hypothesized to be related to root type and structure (Blanco‐Canqui & Ruis, 2020; Nichols et al., 2022). Legumes with extensive tap roots and secondary lateral roots and grasses with extensive fibrous root systems interact with large volumes of soil, compared to brassicas that have a larger tap root with few laterals (tuber‐forming species) and interact with lower volumes of soil.…”

Identifying research priorities through decision analysis: A case study for cover crops

“…It follows that large amounts of agricultural land in the Midwestern US are dedicated to cropping systems that grow only maize and soybean [Boryan et al, 2011; USDA National Agricultural Statistics Service Cropland Data Layer (USDA NASS CDL), 2021]. Utilizing over-wintering cover crops in these systems has been shown to reduce soil erosion and nitrate leaching (Kaspar et al, 2007(Kaspar et al, , 2012Chen et al, 2022), is associated with a reduction in crop insurance losses due to drought, excess heat, and excess moisture (Aglasan and Rejesus, 2021), and possibly offer numerous other context-specific benefits such as increased soil infiltration rates, higher soil water-holding capacity, or increased soil organic matter content (Moore et al, 2014;Basche and DeLonge, 2017;Krupek et al, 2022;Nichols et al, 2022). However, the Midwestern maize-soybean systems present challenges to cover crop adoption.…”