Grain sorghum [Sorghum bicolor (L.) Moench] is the major cereal crop used as staple crop in the arid and semi-arid regions of Ethiopia. Low sorghum yields are attributed to soil, climate and topographic factors. We investigated sorghum yield response to factorial combination of nitrogen and phosphorous (NP) as well as potassium (K), sulphur (S) and zinc (Zn), and how the position of farmers’ fields belonging to different landscape positions (i.e., upslope, mid-slope, and foot slope) could explain fertilizer response and yield variability. The analysis in this study made use of dataset from two sets of on-farm experiments where trials were set at two farmers’ fields for NPKS and three farmers’ fields for NPZn experiments in each landscape position. The experiments were implemented at two sorghum-growing locations (i.e., Hayk and Sirinka) in parts of the north-eastern Amhara region in Ethiopia. Sorghum yield response to fertilizer application was strongly linked to the spatial variation along landscape positions and varied over locations. Fertilizer response was significantly higher at foot slopes compared to mid-slopes and upslope positions, where fields at foot slopes exhibited relatively homogeneous responses. Application of combined nitrogen (N) and phosphorus (P) fertilizers, landscape position and the interaction of fertilizer application and landscape positions strongly affected sorghum yield. There was a linear and significant increase in sorghum yield with the increase in the NP rates. The combined application of NP with different levels of KS as well as NP with Zn fertilizer rates did not result in significant yield difference. The results indicated that local factors were much more influential when accounting for the heterogeneity in sorghum yield response to fertilizer. This further acknowledges the importance of a landscape-based fertilizer management approach to respond yield potential variability related with the farmers’ fields and landscape environment. Further investigation is needed to develop homogeneous fertilizer response units based on spatial variability of soil and topographic attributes along the landscape.

Manufacturers of several POST corn herbicides recommend tank-mixing their herbicides with atrazine to improve performance; however, future regulatory changes may place greater restrictions on atrazine use and limit its availability to growers. Our research objectives were to quantify the effects of tank-mixing atrazine with tembotrione compared to tembotrione alone on (1) weed control, (2) variability in weed control, and (3) sweet corn yield components and yield variability. Field studies were conducted for 2 yr each in Illinois, Oregon, Washington, and Ontario, Canada. Tembotrione at 31 g ha−1 was applied alone and with atrazine at 370 g ha−1 POST at the four- to five-collar stage of corn. The predominant weed species observed in the experiment were common to corn production, including large crabgrass, wild-proso millet, common lambsquarters, and velvetleaf. For nearly every weed species and species group, the addition of atrazine improved tembotrione performance by increasing mean levels of weed control 3 to 45% at 2 wk after treatment. Adding atrazine reduced variation (i.e., standard deviation) in control of the weed community by 45%. Sweet corn ear number and ear mass were 9 and 13% higher, respectively, and less variable when atrazine was applied with tembotrione, compared to tembotrione alone. Additional restrictions or the complete loss of atrazine for use in corn will necessitate major changes in sweet corn weed management systems.

We examine how changes in yield variability affect the welfare of cereal grain and oilseed buyers and producers around the world. We simulate trade patterns and welfare for 21 countries with a Ricardian trade model that incorporates bilateral trade costs and crop yield distributions. The model shows that world trade volumes would need to increase substantially if crop yield variability were to rise. Net welfare effects, however, are moderate so long as countries do not resort to policies that inhibit trade, such as export restrictions or measures to promote self-sufficiency in crops. Low-income countries suffer the most from increases in yield variability, due to higher bilateral trade costs and lower-than-average productivity.

Economic analysis was conducted on hypothetical agronomic research on new crop cultivars for Arkansas dryland soybean and wheat producers. In relation to farmers' attitudes toward risk, the microeconomic effects and level of adoption of yield variability reducing cultivars were analyzed utilizing a production management decision-making model formulated with mathematical programming techniques. The study indicated that negative covariance between crops continues to be an effective means of reducing production risk associated with yield variability. However, under varying circumstances, agronomic research on the breeding of new soybean and wheat cultivars with reduced yield variability is worthwhile if there is only slight concurrent reduction in expected yields.

This article investigates how information from cotton yield monitors influences the perceptions of within-field yield variability of cotton producers. Using yield distribution modeling techniques and survey data from cotton producers in 11 southeastern states, we find that cotton farmers who responded to the survey tend to underestimate within-field yield variability (by approximately 5-18%) when not using site-specific yield monitor information. Results further indicate that surveyed cotton farmers who responded to a specific question about yield monitors place a value of approximately $20/acre/year (on average) on the additional information about within-field yield variability that the yield monitor technology provides.