Agronomy for Sustainable Development

Australia’s farmers are among the most efficient in the world, despite a relatively large gap between potential and achieved water-limited grain yield. With wheat yield gaps typically > 1.7 t/ha or 50% of the water-limited yield, it is important to investigate the degree to which this gap may be attributable to (rational) subprofit-maximising input levels in response to risk and risk aversion in many major grain-growing regions, particularly those with lower and more variable rainfall. Here, we use a set of 14 case study sites across the Australian wheatbelt to examine the risk-return profile of several agronomic management practices and show the extent to which the farmers’ risk attitude determines their decision-making. Using a novel profit-risk-utility framework that incorporates crop simulation, probability theory, finance techniques and risk-aversion analysis, we were able to better demonstrate how farmers might select practices that manage economic risk across sites ranging from low to high rainfall. Results varied with risk preference and yield potential. However, there are real opportunities to close the yield gap by adopting non-limiting or near non-limiting nitrogen fertiliser practices and controlling fallow weeds. We show for the first time that yields associated with current best practice can be surpassed for most levels of risk aversion by adopting an emergent practice of optimising the site-specific time of sowing and matching variety to time of sowing. For some sites and risk profiles, the emerging best practice package which includes additional N fertiliser is also profitable under risk. We also propose a modified integrated framework for yield gaps. Here, we distinguish allocative input constrains due to risk aversion from those due to access to resources, and we account for an innovation gap where the current agronomic frontier is shifted upwards by growers successfully, implementing new technologies that are not yet part of current best practice.

Since the 1940s, the introduction of plastic technology caused a true revolution in agriculture. Among the uses of plastics, mulch films have been used to improve yields and crop traits. They are useful to increase air and soil temperatures, protect plants from several agents, improve water management, reduce the growth of weeds, and, consequently, to avoid high dependence on agrochemicals. The low-density polyethylene obtained from non-renewable resources has been mainly used for this purpose due to its mechanical and barrier properties, resistance to all forms of degradation, easy processing and low cost. Unfortunately, low-density polyethylene presents several economic and environmental drawbacks related to their low biodegradability, their removal after the crop cycle and their final disposal. Hence, there is a great interest in using biodegradable mulch films to provide greater agricultural sustainability. In this review, we interpret evidence about the potential of polysaccharide-based bio-composite mulch films as a possible replacement of traditional low-density polyethylene films as well as their commercial barriers and evolution of intellectual property rights. We identified that: (1) mulch films improve their mechanical properties through the formulation of multiphase materials, reaching international standards; (2) biodegradability of bio-composite mulch films can be adjusted according to crop season; (3) bio-composite mulch films provide high yields for different crops; and (4) they are promising for the management of pests and weeds. Due to these traits, biodegradable mulch films have reported a significant increase in the number of patent protections lately. However, to the present day the lack of knowledge about bio-composite mulch films and their high costs are the main commercial limitations to their adoption for crop production systems in the field.

The ability of agriculture to adapt to environmental changes and to address main issues of food quality and environment protection is a fundamental factor in achieving sustainability. Low yield capacity of contemporary sustainable farming systems, however, is a major obstacle to future growth of sustainable agriculture. In addition, increasing pressure is placed for higher food supply due to the projected population increase. To overcome these barriers and stimulate the wide adoption of sustainable agriculture, ample supply of cultivars that satisfy the requirements for sustainability without compromising productivity is essential. Otherwise, the viability of sustainable agriculture is unsound. Moreover, plant breeding has to be a non-stop process supporting agriculture because of the ongoing climate changes. The studies of the effects of competition on crop yield and selection efficiency unravelled important findings for plant breeders. Firstly, the uppermost cultivar type is the mono-genotypic and particularly the highest evolutionary grade of ‘pure line’. Secondly, single plant selection is effective only when it is realized in the absence of competition for growth resources. Honeycomb methodology, by considering as a major principle the application of selection in the absence of competition, counteracts the disturbing effects of competition on selection effectiveness. Furthermore, the honeycomb experimental designs cope with the confounding implications of soil heterogeneity. These two findings help breeders to consider the individual plant as an evaluating and selection unit. As a consequence, the development of pure line cultivars that fully meet the needs of a sustainable agriculture is possible. Most importantly, honeycomb breeding exploits effectively not only favourable but marginal environments as well through the development of density-neutral cultivars. Marginal environments are exploited optimally when lower plant populations are used. It is of essence to realize that without the ability of exploiting successfully marginal environments which represent the majority of the production environments globally, sustainability in agriculture becomes problematic.