Tactical crop management for improved productivity in winter-dominant rainfall regions: A review

Abstract

This study reviews published information on the tactical management decisions needed to maximise economic grain yield in winter-dominant rainfall regions of the Mediterranean type. Tactical decisions are defined as those relating to the period from immediately before sowing to harvest. Tactical management is the principal means by which farmers respond to changing environmental and short-term economic conditions as the season progresses. The review considers published evidence that underpins these decisions and relates to cereal crops (wheat, barley and oats), pulse crops (field pea, faba bean, chickpea and narrow-leaved lupin) and canola. The criteria used to guide management decisions during the season involve soil and tissue tests for nutrients, knowledge of weed numbers and resistance status in the current and previous seasons, weather conditions that favour disease development, and knowledge of thresholds and biology of insect pests that may warrant control measures. All of these decisions can be related to the timing of the opening rains and the length of the growing season; the crop, pasture or weeds present in the previous two seasons; the presence of pest-and disease-bearing crop residues; and the type of tillage in use. Most of these indicators require further refinement through research across environments, soil types, crop types and production systems. The likely interactions between tactical or short-term management decisions, longer term or strategic decisions, and genetic factors are discussed. The prevalent use of chemicals in the management of biotic factors that can impact the crops is noted, as is progress towards various systems of 'integrated' management of these threats to crop production. Most tactical decisions in rainfed cropping systems appear to be supported by adequate evidence, although some decisions are still based on practical experience and observations. Application of tactical management practices together with strategic management and use of improved genotypes provides the possibility of achieving rainfall-limited potential grain yield at a regional scale. The papers reviewed have been selected partly on the basis that the experimental treatments achieved the estimated potential grain yield. Where the potential grain yields are not being achieved in commercial crops, it remains unclear whether this is due to inadequate adoption of existing information or inadequate research to identify and address the underlying causes. We highlight the need to devise a simple decision aid to assist farmers and their advisers to respond to the variable seasonal conditions evident since the turn of the Century.