Dryland cropping system intensification in the West-Central Great Plains: Impacts and barriers to adoption

View the project final report

• 2016 annual report

Commodities

• Agronomic: wheat

Practices

• Crop Production: continuous cropping, cropping systems, crop rotation, fallow, fertilizers, no-till, nutrient cycling, nutrient management
• Education and Training: Film
• Natural Resources/Environment: carbon sequestration, soil stabilization
• Production Systems: agroecosystems, dryland farming, holistic management
• Soil Management: nutrient mineralization, organic matter, soil microbiology, soil quality/health
• Sustainable Communities: new business opportunities, social networks

Efficient precipitation management is imperative for sustainable dryland cropping systems in the West-Central Great Plains where water is the primary yield-limiting factor. In conjunction with no-till, cropping system intensification (reducing fallow frequency) is an effective method of enhancing precipitation use efficiency, leading to increases in annualized grain production, greater net farm income, and improved soil quality.However, winter wheat-fallow remains the dominant dryland crop rotation in the West-Central Great Plains. In this region, over 15 million acres in the wheat-fallow rotation degenerate soil productivity and contribute to long-term environmental and economic degradation. Increasingadoption of intensified rotations could have enormous implications for profitability, carbon sequestration, food production, and soil erosion, as well as possible improvements in soil structure and drought tolerance that are poorly understood. My research objectives are to identify the barriers to cropping intensification and the resources needed to eliminate or reduce the frequency of fallow in crop rotations and to quantify the effects of intensification on soil structure and drought tolerance.Using an integrated social-ecological approach, I will examine the sociological and biophysical dimensions of cropping intensification. I will interview 30 no-till, dryland farmers across a gradient of cropping intensity to evaluate internal and external factors that influence farmerdecision-making and identify the motivations and farmer-employed strategies that have enabled successful transitions to intensified rotations. Alternative crop rotations have been experimentally evaluated, but there is little research-based information concerning strategies that farmers employ to intensify rotations or the motivations that drive the transition.Through on-farm soil and plant sampling, I will 1) quantify the effects of crop rotation on aggregation and drought tolerance; and 2) measure the arbuscular mycorrhizal (AM) fungal biomass and colonization of winter wheat roots that mediate aggregation and water and nutrient uptake to generate a mechanistic understanding of these processes. Cropping intensity has improved soil physical properties in cropping system experiments, but the extent to which farmers are experiencing a similar benefit has not been examined. In addition, few studies have examined crop rotation effects on fungal biomass and root colonization or the link between AM fungi and drought tolerance under field conditions.I will disseminate these findings through peer-reviewed journals, presentations at regional farming conferences, in an article for a popular farming magazine, and on a website I will create as a resource base for producers who may be considering alternative cropping rotations. A short film will be made based on producer interviews to increase public awareness of the sustainability challenges in this region and to highlight innovative solutions. The wheat-fallow cropping system is not an economically or environmentally viable strategy moving forward, and this research will help identify and mobilize the most effective resources for enabling producers to adopt sustainable practices.

Objective 1: Identify the social, ecological, political, and economic barriers to cropping intensification and the resources needed to eliminate or reduce the frequency of fallow in crop rotations.

Sub-objective 1: Examine the strategies farmers have employed to successfully intensify their cropping systems, and the obstacles faced by farmers with higher frequencies of fallow.
Sub-objective 2: Identify the factors that influence farmer decision-making at multiple scales.
Sub-objective 3: Identify the most effective educational, social, or political resources that could be mobilized to enable producers to intensify crop rotations.

Objective 2: Quantify cropping intensity effects on wheat and annualized grain yields, soil structure, and AM fungi across management and climatic gradients.

Sub-objective 1: Compare winter wheat yields and annualized grain yields across farms with varying cropping intensity.
Sub-objective 2: Quantify cropping intensify effects on aggregate size and stability, intra-aggregate organic carbon, bulk density, and soil organic carbon.
Sub-objective 3: Assess the effect of AM fungal abundance on soil aggregation dynamics.

Objective 3: Quantify the relationships between cropping intensity, mycorrhizal colonization, and drought tolerance in winter wheat.

Sub-objective 1: Quantify AM fungal colonization of winter wheat roots and wheat canopy temperature as an indicator of drought stress.