The role of crop rotations in determining soil structure and crop growth conditions

Abstract

. 2005. The role of crop rotations in determining soil structure and crop growth conditions. Can. J. Soil Sci. 85: 557-577. Increasing concern about the need to provide high-quality food with minimum environmental impact has led to a new interest in crop rotations as a tool to maintain sustainable crop production. We review the role of rotations in the development and preservation of soil structure. After first introducing the types of rotations in current practice and their impact on yield, we assess how soil and crop management in rotations determines soil structure, and in turn how soil structure influences crop growth and yield. We also briefly consider how soil structure might contribute to other beneficial effects of rotations, namely nutrient cycling and disease suppression. Emphasis is given to the influence of crop choice and, where relevant, interaction with tillage system and avoidance of compaction in the improvement and maintenance of soil structure. Crop rotations profoundly modify the soil environment. The sequence of crops in rotation not only influences the removal of nutrients from a soil, but also the return of crop residues, the development and distribution of biopores and the dynamics of microbial communities. These processes contribute to the development of soil structure. We have identified areas where further research is needed to enable the potential benefits of rotations in the management of soil structure to be fully exploited. These include: improved quantitative linkages between soil structure and crop growth, the consequences to soil structure and nutrient cycling of crop residue incorporation, developing natural disease suppression, amelioration of subsoils by crop roots, the fate of carbon deposited by plant roots in soil and the fate of organic nitrogen in soil. Les auteurs passent en revue le rôle de l'assolement dans l'évolution et la préser-vation de la structure du sol. Après avoir présenté les diverses méthodes d'assolement en usage et leur incidence sur le rendement, ils expliquent comment la gestion du sol et des productions végétales durant la rotation affecte la structure du sol et comment cette dernière agit sur la croissance et le rendement des plantes. Les auteurs examinent aussi brièvement la manière dont la structure du sol pourrait contribuer autrement aux effets bénéfiques de l'assolement, notamment dans le cycle des éléments nutritifs et la lutte contre la maladie. Ils insistent sur l'incidence du choix de la culture et, quand la chose est pertinente, sur l'interaction avec le système de travail du sol et la nécessité d'éviter le compactage si l'on veut améliorer ou préserver la structure du sol. L'assolement modifie considérablement l'environnement tellurique. Les cultures qui se succèdent lors de la rotation n'influent pas seulement sur le retrait des éléments nutritifs dans le sol, mais aussi sur la réintégration des débris végétaux, sur le développement et la réparti-tion des biopores et sur la dynamique de la microflore. Ces processus concourent au développe...

Soil structure, organic matter and earthworm activity in a comparison of cropping systems with contrasting tillage, rotations, fertilizer levels and manure use

“…The role of crop rotations in determining soil structure and crop growth conditions has been recognised as being of prime importance for sustainable crop production (Ball et al, 2005). In organic cropping, the management of grass swards is of particular interest for the maintenance of soil structure (Ball et al, 2007).…”

Reclamation of a Degraded Coal-Mining Area with Perennial Cover Crops

“…Materechera et al (1992) also observed a lower proportion of large aggregates in agricultural clay soils cultivated with Lolium multiflorum compared to Triticum spp and Pisum sativum, attributing this result to the greater root length of Lolium multiflorum. The root system of grasses can lead to the change of more compact aggregates into less compact aggregates (Portella et al, 2012) by breaking the aggregates and then reshaping them (Terpstra, 1990) or by stresses generated in the soil-root interface during water extraction, which cause cracks in the soil (Ball et al, 2005).…”

Managing excess water in Canadian prairie soils: A review

“…Soil structure can also influence the rooting pattern by inhibiting the downward growth of roots into horizons with a greater bulk density (such as solonetzic Bnt horizons) or by causing roots to cluster within certain zones in the soil. These patterns can negatively impact the ability of roots to take up both moisture and nutrients, necessarily reducing yield (Ball et al 2005). …”

“…It can reduce plant-available water by twice as much as continuous cropping alone, and by more than four times as much as a crop-fallow system (Eilers et al 1995). Compared with continuous annual crops and pastures, alfalfa provides a threefold increase in the number of large pores (2 mm) in the subsoil and these pores persist for 2 yr or more after the alfalfa has been removed, improving infiltration (Ball et al 2005). It is also a high-water use plant, and with its deep roots, serves to draw down the water table to a much greater depth than annual crops, reducing the risk of secondary salinity associated with a shallow water table (Ridley et al 2001).…”

“…For example, more large pores were observed in a clay loam soil under 24 yr of no-till compared with conventional tillage (Miller et al 1999), which would have a significant impact on infiltration and drainage. Reductions in tillage frequency and depth can also improve soil structure by minimizing aggregate breakdown and decreasing compaction damage (Ball et al 2005). Improved aggregation is a critical component of improving infiltration and minimizing standing water.…”