David I. Gustafson

Sustainable use of glyphosate in North American cropping systems

Roundup Ready (glyphosate-resistant) cropping systems enable the use of glyphosate, a non-selective herbicide that offers growers several benefits, including superior weed control, flexibility in weed control timing and economic advantages. The rapid adoption of such crops in North America has resulted in greater glyphosate use and concern over the potential for weed resistance to erode the sustainability of its efficacy. Computer modeling is one method that can be used to explore the sustainability of glyphosate when used in glyphosate-resistant cropping systems. Field tests should help strengthen the assumptions on which the models are based, and have been initiated for this purpose. Empirical evaluations of published data show that glyphosate-resistant weeds have an appearance rate of 0.007, defined as the number of newly resistant species per million acres treated, which ranks low among herbicides used in North America. Modeling calculations and ongoing field tests support a practical recommendation for growers occasionally to include other herbicides in glyphosate-resistant cropping systems, to lower further the potential for new resistance to occur. The presented data suggest that the sustainability of glyphosate in North America would be enhanced by prudent use of additional herbicides in glyphosate-resistant cropping systems.

Climate change: a crop protection challenge for the twenty-first century

Convincing data now show that temperatures are increasing, and that changing precipitation patterns are already affecting agriculture. Predicted future impacts vary by region, but all are projected to suffer productivity declines by the late twenty-first century unless successful mitigation measures are implemented soon. Exacerbating the climate change challenge, doubling of overall crop productivity will be required by mid-century. Clearly, crop protection will become increasingly difficult as higher-yielding varieties present a larger and more tempting target to all pests, and the pests themselves extend their ranges poleward and into other new geographies owing to reduced winter kill and longer growing seasons. Fortunately, good progress on enhancing crop protection technology to meet these challenges is already being made, but the scope of this climatic provocation is such that complacency is not an option. Increased investment into new technologies and adoption of new agricultural practices with improved adaptive and mitigation potential are both essential.

Climate adaptation imperatives: untapped global maize yield opportunities

Climate change represents an unavoidable and growing challenge to food security, imposing new adaptation imperatives on all farmers. Maize is arguably the worlds most productive grain crop, as measured by grain yield. However, maize yields vary dramatically due to many factors, including soils, climate, pests, disease, agronomic practices, and seed quality. The difference between observed yields and those achievable by optimized crop production methods is called the yield gap. In this work we quantified the current yield gap for 44 countries through the use of a large private-sector data set recently made available to the crop modelling community. The yield gap was quantified for three groups of countries, categorized by level of intensification. Observed yield gaps for high, medium, and low levels of intensification are 23%, 46%, and 68%, respectively. If all maize production countries were able to shrink their yield gap to 16.5% (as in the USA) an additional 335 million metric tons (MMT) of maize grain would be produced. This represents a 45% increase over the 741 MMT produced by these countries in 2010. These data demonstrate that a major untapped maize yield opportunity exists, especially in those countries where intensification has not kept pace with the rest of the world.

Multi-indicator sustainability assessment of global food systems

Food systems are at the heart of at least 12 of the 17 Sustainable Development Goals (SDGs). The wide scope of the SDGs call for holistic approaches that integrate previously “siloed” food sustainability assessments. Here we present a first global-scale analysis quantifying the status of national food system performance of 156 countries, employing 25 sustainability indicators across 7 domains as follows: nutrition, environment, food affordability and availability, sociocultural well-being, resilience, food safety, and waste. The results show that different countries have widely varying patterns of performance with unique priorities for improvement. High-income nations score well on most indicators, but poorly on environmental, food waste, and health-sensitive nutrient-intake indicators. Transitioning from animal foods toward plant-based foods would improve indicator scores for most countries. Our nation-specific quantitative results can help policy-makers to set improvement targets on specific areas and adopt new practices, while keeping track of the other aspects of sustainability.The development of sustainable food systems requires an understanding of potential trade-off between various objectives. Here, Chaudhary et al. examine how different nations score on food system performance across several domains, including environment, nutrition, and sociocultural wellbeing.

Field calibration of SURFACE: a model of agricultural chemicals in surface waters.

Abstract Coal fly ash, an industrial solid waste, was found to have a good adsorption capacity for iron. The effect of various parameters affecting the adsorption, such as bed depth, initial concentration of solute, pH etc. has been determined by column studies. The adsorption of iron on coal fly ash conforms to Freundlichs adsorption model. Removal of iron from several natural water samples was investigated and showed the effectiveness for iron removal from natural water. The common water quality parameters were analysed in the influent and effluent waters.

Climate adaptation imperatives: global sustainability trends and eco-efficiency metrics in four major crops - canola, cotton, maize, and soybeans

Supplying our worlds growing nutrition needs in more sustainable ways has become an urgent global imperative, given the constraints of finite resources and the challenges of accelerating climate change. We present national-level eco-efficiency metrics in several representative production countries during the most recent decade (2000–2010) for four important crops: canola, cotton, maize, and soybeans. The metrics address greenhouse gas emissions and the utilization of land, water, and energy – all calculated per unit of production. We group countries based on their level of agricultural intensification and find that high-intensification countries are achieving the highest and yet still increasing levels of eco-efficiency, with these decadal gains: canola (26%), cotton (23%), maize (17%), and soybeans (18%). By stark contrast, low-intensification countries had no change in eco-efficiency during this same decade. Overall, our results suggest large opportunities for additional improvements in the developing world, and that cumulative resource savings through intensification have been significant. For instance, in the case of irrigated maize, if the high- and medium-intensification production countries had only achieved the same irrigation water-use efficiency as in the low-intensification countries, approximately 4 quadrillion (4×1015) more litres of irrigation water would have been consumed during the period 2000–2010.

Use of computer models to assess exposure to agricultural chemicals via drinking water

Surveys of drinking water quality throughout the agricultural regions of the world have revealed the tendency of certain crop protection chemicals to enter water supplies. Fortunately, the trace concentrations that have been detected are generally well below the levels thought to have any negative impact on human health or the environment. However, the public expects drinking water to be pristine and seems willing to bear the costs involved in further regulating agricultural chemical use in such a way so as to eliminate the potential for such materials to occur at any detectable level. Of all the tools available to assess exposure to agricultural chemicals via drinking water, computer models are one of the most cost-effective. Although not sufficiently predictive to be used in the absence of any field data, such computer programs can be used with some degree of certainty to perform quantitative extrapolations and thereby quantify regional exposure from field-scale monitoring information. Specific models and modeling techniques will be discussed for performing such exposure analyses. Improvements in computer technology have recently made it practical to use Monte Carlo and other probabilistic techniques as a routine tool for estimating human exposure. Such methods make it possible, at least in principle, to prepare exposure estimates with known confidence intervals and sufficient statistical validity to be used in the regulatory management of agricultural chemicals.

Modeling root zone dispersion: a comedy of error functions

Abstract The assumption of constant dispersion coefficient is ubiquitous in the modeling of pesticide transport through the root zone. This assumption is critically examined and found to be invalid in most lab and field studies. An improved model is proposed and tested in which it is assumed that the dispersion coefficient grows linearly with time and distance traveled. Ways in which this improved representation of dispersion could be incorporated into existing models of pesticide transport are discussed.

Nutritional Sustainability: Aligning Priorities in Nutrition and Public Health with Agricultural Production

Nutrition science-based dietary advice urges changes that may have a great impact on agricultural systems. For example, the 2016 Dietary Guidelines for Americans (DGA) recommends greatly increased fruit and vegetable consumption, but the present domestic production is insufficient to accommodate large-scale adoption of these guidelines. Increasing production to the extent needed to meet the DGA will necessitate changes in an already stressed agriculture and food system and will require nutrition and agriculture professionals to come together in open and collegial discourse. All involved need to understand the stress placed on the food system by increasing populations, changing diets, and changing environments, and recognize the major diet-based public health challenges. Furthermore, there is a need to understand the intricate interplay of the myriad parts of the food system and the vast amount of work necessary to make even small changes. New systems approaches are needed, especially at the research level, where nutrition, public health, agriculture, and the food industry work together to solve interconnected problems. Future well-being depends on a sustainable food system that continues to deliver optimal health with minimal impact on the environment.

Greenhouse gas emissions and irrigation water use in the production of pulse crops in the United States

Abstract Supplying our world’s growing nutrition needs in more sustainable ways has become an urgent global imperative, given the constraints of finite resources and the challenges of accelerating climate change. Pulse crops, which are the dried seeds of legumes such as dry peas, chickpeas, beans, and lentils, play a key role in maintaining affordable, nutritious diets, as they provide high amounts of protein and fiber, and relatively low amounts of fat. As legumes, they are also advantageous from an environmental perspective, because they fix atmospheric nitrogen, thereby reducing the need for added fertilizers. Although some pulse crops are produced in areas that require irrigation, more than 80% of the pulse crop production area in the United States is exclusively rain-fed. In order to quantify eco-efficiency metrics associated with the production of pulse crops in the United States, life cycle assessment techniques were used to calculate “cradle to farm-gate” greenhouse gas emissions and irrigation water use, both on a per unit of production basis. The results demonstrate that pulse crops have low carbon and water footprints relative to most foods, with greenhouse gas emissions of 0.27 kg CO2e/kg and irrigation water use of 0.19 m3/kg, both as national averages across all 2.4 MMT (millions of metric tons) of pulse crops currently produced annually in the United States.