Contributions and interactions of cultivations and rotations to soil quality, protection and profitable production.

Abstract

Crop rotation must be considered a key component in wheat-dominated arable crop production systems, irrespective of the method of soil cultivation for crop establishment, with maximum use made of break crops that contribute to soil structural stability, soil quality, resilience, and soil fertility. For crop protection strategies in reduced cultivation/conservation tillage systems, selection and positioning of crops in cropping sequences provide options not only for decreased pest and disease carry but permit more selective decision-making and rotational control of grass weeds in broad-leaved crops without the use of persistent herbicides. The integration of different cultivation systems with crop rotation also helps to achieve an increase in soil cover index thereby minimising soil erosion and nitrate losses, and provides increases in species diversity which had implications for natural regulation of antagonists. Integrating different cropping sequences with reduced cultivation systems also contributes to maintenance/improvement in organic matter annual balance. These issues are mainly addressed in the intercrop period and have a marked influence on subsequent pest, disease and weed population dynamics and, hence, risk. However, in reduced tillage systems, decision-making processes are knowledge-intensive and, as there are few practising 'min-till' farmers and the advice these farmers receive is insufficient and sometimes conflicting, their crop management expertise increases.
Soil is the basis of all agricultural production thus conservation and improvement of this valuable resource must be the highest priority. This allows produce to be grown on healthy and biologically active soil with a satisfactory level of organic matter, a good physical structure and sufficient fertility. Reduced cultivation/conservation tillage systems and appropriate agronomic management practices, improve efficiency and profitability of production, reduce soil degradation, improve soil health, and protect the environment. Integrating rotations, by selecting break crops with lower amounts of fragile crop residue and with low C:N rations (oilseeds or pulse legumes) with main crops that produce high amounts of non-fragile crop residue and high C:N ratios (cereals) enables not only better crop residue management but also the natural conditioning and structural improvements in soil through their differing root structures, architectures and soil penetrating properties.