Impact of Manure Application on Phosphorus in Surface Runoff and Soil Erosion

Effects of method of manure management and dietary P were compared on 21 natural runoff plots to monitor the long-term impact of dietary P to P losses in runoff and erosion. Reducing feed P resulted in a 33% reduction in manure P content and soil test P buildup and runoff losses of P also were directly proportional to feed P inputs. The timing and management of manure are also important considerations for controlling P losses in runoff in the year of application. However, residual effects of timing and management are probably small. Management criteria designed to assess the potential for landscape P-loading (i.e. “P-index”) correctly weight winter applications as more detrimental than planting time applications

Corn Yield Potential and Optimal Soil Productivity in Irrigated Corn/Soybean Systems

In 1999, an interdisciplinary research team at the University of Nebraska established a field experiment to (1) quantify and understand the yield potential of corn and soybean under irrigated conditions, (2) identify efficient crop management practices to achieve yields that approach potential levels, and (3) determine the energy use efficiency, global warming and soil C-sequestration potential of intensively managed corn systems. The experiment compares systems that represent different levels of management intensity expressed as combinations of crop rotation (continuous corn, corn-soybean), plant density (low, medium, high) and nutrient management (recommended best management vs. intensive management). Detailed measurements include soil nutrient dynamics and C balance, crop growth and development, nutrient uptake and components of yield of corn and soybean, radiation use efficiency, soil surface fluxes of greenhouse gases, root biomass, C inputs through crop residues, translocation of non-structural carbohydrates, and amount, composition and activity of the microbial biomass. Selected results for corn are presented

Corn Yield Potential and Optimal Soil Productivity in Irrigated Corn/Soybean Systems

In 1999, an interdisciplinary research team at the University of Nebraska established a field experiment to (1) quantify and understand the yield potential of corn and soybean under irrigated conditions, (2) identify efficient crop management practices to achieve yields that approach potential levels, and (3) determine the energy use efficiency, global warming and soil C-sequestration potential of intensively managed corn systems. The experiment compares systems that represent different levels of management intensity expressed as combinations of crop rotation (continuous corn, corn-soybean), plant density (low, medium, high) and nutrient management (recommended best management vs. intensive management). Detailed measurements include soil nutrient dynamics and C balance, crop growth and development, nutrient uptake and components of yield of corn and soybean, radiation use efficiency, soil surface fluxes of greenhouse gases, root biomass, C inputs through crop residues, translocation of non-structural carbohydrates, and amount, composition and activity of the microbial biomass. Selected results for corn are presented

Impact of Manure Application on Phosphorus Runoff and Soil Erosion

Phosphorus (P) losses from agricultural land is a serious environmental issue because of the impact of P on freshwater eutrophication (McDowell, et al., 2001). The movement of P from soil to surface water is impacted by P input to soil and manure management practices that impact P transport processes. Twenty-one natural runoff plots were established to monitor the effect of time and method of composted beef feedlot manure application and feed P input on net losses of bio-available P and sediment in surface runoff. Reducing feed P inputs resulted in a 33% reduction in manure P content. Runoff losses of P were reduced in direct proportion to feed P inputs. Runoff volume and sediment losses were lowest in the year s of compost application and we observed that a longer time interval between compost application date and spring runoff season resulted in increase sediment, runoff and P loss. Bray-PI extractable soil P (0-15cm) increased from 27 ppm prior to compost application up to 400 ppm in direct proportion to manure P loading rate. Management criteria designed to assess the potential for landscape P loading (i.e. P-index ) correctly weight winter· applications as more hazardous than planting time applications. Results indicate that reduction of P input at the feedlot will have a long-term impact in reducing P loading to surface waters

Understanding Corn Yield Potential And Optimal Soil Productivity In Irrigated Corn Systems

In 1999, a field experiment was established to (I) quantify and understand the yield potential of corn and soybean under irrigated conditions, (2) identify efficient crop management practices to achieve yields that approach potential levels, and (3) determine the energy use efficiency, global warming and soil C-sequestration potential of intensively managed corn systems. The experiment compares systems that represent different levels of management intensity expressed as combinations of crop rotation (continuous corn, corn-soybean), plant density (low. medium. high) and nutrient management (recommended best management vs. intensive management). Detailed measurements include soil nutrient dynamics and C balance, crop growth and development, nutrient uptake and components of yield of corn and soybean, radiation use efficiency, soil surface fluxes of greenhouse gases, root biomass, C inputs through crop residues, translocation of non-structural carbohydrates, and amount, composition and activity of the microbial biomass. Data collected from 1999 to 2001 suggest that 0) current fertilizer recommendations do not allow expression of full attainable yield, (ii) high corn yields require higher plant density (37,000 to 44,000 plants/acre) and greater N and K uptake per unit yield, (iii) existing corn growth simulation models underestimate the actual dry matter production and yield measured at near-optimum growth conditions in the field, and (iv) the potential to increase C sequestration is greatest in continuous corn systems with intensive managemen

Understanding Corn Yield Potential in Different Environments

The UNL research program on Ecological intensification of irrigated maize-based cropping systems aims to (i) improve understanding of the yield potential of corn and soybean and how it is affected by management, (ii) develop a scientific basis for evaluating yield potential at different locations, (iii) develop practical technologies for managing intensive cropping systems at 70-80% of the yield potential, and (iv) conduct integrated assessment of productivity, profitability, input use efficiency, soil carbon sequestration, energy and carbon budgets, and trace gas emissions. Results of this work have been reported earlier (Arkebauer et al., 2001; Dobermann et al., 2002). In this paper we discuss examples of progress made in 2002, focusing on obtaining additional data sets from high-yield environments and on using crop simulation modeling for understanding yield potential