Tillage and Cover Cropping Effects on Aggregate‐Protected Carbon in Cotton and Tomato

Abstract

T he soil C sequestration potential of reduced tillage or CT has been extensively studied in other parts of the country, but there has been very little CT research under arid, irrigated agriculture systems, like those in California. California cropping systems are intensively managed and require tillage operations to address furrow irrigation needs. Diverse crop rotations and crops untested for reduced tillage regimes have complicated the development of CT approaches in this highly productive agricultural region. Reducing tillage of agricultural soils may improve agricultural sustainability by reducing fossil fuel consumption, labor needs, equipment maintenance, and soil erosion, and increase soil water conservation and soil C sequestration (Unger et al., 1997; Lal, 2001). Soil C sequestration potential is dependent on a number of factors including climate and parent material. California agricultural soils often have high clay content (loam to loamy clay) because of the depositional environment of the San Joaquin Valley. As a result, these soils may have a greater potential to promote organo-mineral interactions and stabilize C through aggregation; however, irrigation combined with California's warm climate (near-surface soil temperatures often averaging between 25 and 35°C) may enhance decomposer activity and limit the potential for soil C sequestration.

Biological and other soil parameters response to winter cover crops in a mediterranean irrigated system

“…There are studies which showed the necessity of long term experiments to obtain benefits in the TOC contents. However, in our study higher TOC were found in the CC treatments since 2012 that are in agreement with other short term experiments (Nivelle et al, 2016;Veenstra et al, 2007). Particularly, Villamil et al (2006) and Mazzoncini et al…”

“…From 2008 until 2016, there were increases of 39% after barley, 36% after vetch and 25% after fallow. Some studies showed that the combination of no tillage and use of CC is necessary to increase the TOC content (Nivelle et al, 2016;Veenstra et al, 2007).…”

“…The shift to more sustainable agricultural practices such as minimum tillage or including winter cover crops (CC) in the last decades is improving soil structure and protecting the soil from wind and water erosion. Cover cropping also enhances soil organic matter (SOM) content, aggregation stability and microbial activity (Ding et al, 2006;Kabir and Koide, 2000;Mendes et al, 1999;Muñoz et al, 2007;Veenstra et al, 2007). However, in semiarid climate areas with limitations of water availability and nutrients uptake, the benefits of CC establishment do not seem to be clear, showing in some cases reductions in the main crop yield (Lascano et al, 2015;Salmerón et al, 2010).…”

“…Total organic carbon (TOC) content is a soil quality indicator that is affected by the changes in the crop management such as intensive tillage and the addition of crop residues to the soil (Chavarría et al, 2016;Muñoz et al, 2007;Nivelle et al, 2016;Veenstra et al, 2007;Villamil et al, 2006). Benefits in soil structure are related to its accumulation in the soil and an increase in the formation and stabilization of soil microaggregates and macroaggregates (Beare et al, 1994).…”

Nitrogen supply from fertilizer and legume cover crop in the transition to no-tillage for irrigated row crops

“…Use of cover crops can bring increases in soil organic matter and related benefits under both types of management (Lal et al 1998b;Veenstra et al 2007), and can be an important part of long-term and short-term fertility programs. In developing a management approach for reduced tillage alternatives, it is important to understand the N supplied by as well as any interactions between fertilizer and cover crops.…”