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Solutions to simultaneously meet crop phosphorus (P) demand and reduce P loss from agricultural systems are required to improve the sustainability of our production. Our objective was to determine the effect of cover crop addition (with cover crop [CC], and without cover crop [NC]) and P fertilizer management (zero P control [CN], fall broadcast [FB], and spring injected [SI]) on P cycling, agronomic P use efficiency (PUE), and environmental P use efficiency (EPUE), measured as the percent of P lost in runoff water, in a no‐till corn (Zea mays)–soybean [Glycine max (L.) Merr.] rotation. The experiment was a 2 × 3 factorial. Both FB and SI increased P cycling through the main crop and cover crop tissue, compared to the CN. Cover crop did not affect main crop P uptake, removal in grain, or return to soil in crop residue, but CC treatment increased total P uptake and return in the system. Cover crop effects on P uptake, removal, and return were the same regardless of P fertilization treatments. Phosphorus fertilizer and CC treatments did not affect PUE. Both FB and SI P fertilizer management decreased EPUE, although SI tended to decrease EPUE less than FB. Cover crop significantly improved EPUE only in 2019, when CC reduced erosion losses. Therefore, cover crops were not consistently beneficial for reducing the environmental effects of P fertilization, and their use cannot replace the importance of sound P fertilizer stewardship, including sub‐surface P placement. However, cover crops play an important role in improving EPUE in years with high erosion loss potential. Core Ideas: Cover crops increased total P return to the soil surface by 30%.Agronomic phosphorus use efficiency was not affected by cover crops or phosphorus fertilizer management.Cover crops had variable effects on environmental phosphorus use efficiency.Reducing P loss is the most important factor for improving environmental P use efficiency. [ABSTRACT FROM AUTHOR]

Trends in animal production have moved the industry toward large confined animal feeding operations (CAFOs). These CAFOs concentrate large amounts of manure-based nutrients in relatively small areas, which increases the risk of nutrient loss to the surrounding environment. In response to water quality concerns, P-based manure application regulations are becoming more common. Mr. Pritchard is the owner and operator of two 4500-head swine ("Sus scrofa") farms located in an area of intensive animal production in North Carolina. He has noticed an increasing trend in the soil P concentrations in his manure application fields and realizes that he does not have enough land to apply his anaerobically treated liquid swine manure based on crop P uptake. Mr. Pritchard is now faced with the dilemma of what to do to slow down the P accumulation in his soil. This case constructs a P budget for Mr. Pritchard's farm to examine ways of balancing on-farm nutrients. Students are encouraged to explore solutions related to animal nutrition, crop production, water quality, soil chemistry, and manure management. Furthermore, students should evaluate the appropriate role of government and industry in assisting Mr. Pritchard to protect the environment while remaining a profitable swine producer.

Producers relying on the traditional central Great Plains cropping system of winter wheat (Triticum aestivum L.)-fallow could increase crop yield and resource sustainability by changing to more diverse crop rotations. Crops suited to the variable timing and amount of precipitation characteristic of this region need to be identified so that rotations can be diversified. This study was conducted to determine the effects of water deficit at various growth stages on leaf area index, plant height, yield components, soil water extraction pattern, and seasonal water use of black bean (Phaseolus vulgaris L). The study was conducted during the 1995 and 1996 growing seasons near Akron, CO, on a Rago silt loam (fine, montmorillonitic, mesic Pachic Argiustoll). An automated rainout shelter was used to eliminate precipitation. Irrigation treatments consisted of withholding water at vegetative, reproductive, or grain-filling growth stages. All treatments received 18.3 cm of water during the growing season. Water stress during the vegetative growth stage produced the shortest plants with the least leaf area. Soil water extraction and total water use were also least when water was withheld during the vegetative stage. Seed yield was reduced because of reductions in pods per plant and/or seeds per pod when water stress occurred during the reproductive stage. Black bean appears to have potential as a dryland rotation crop in the central Great Plains when soil water profiles are near field capacity at planting and normal to above normal precipitation is expected., The traditional dryland cropping system of the central Great Plains is winter wheat-fallow, in which one wheat crop is grown every 2 yr. The fallow period covers approximately 15 mo. [...]

Porous plates or cups are commonly used to collect soil solution samples in field studies or from intact soil columns. Some commonly used materials for porous plates may adsorb soil solution constituents such as phosphorus (P). An alternative to using a porous plate is to use a membrane filter with a known pore size and bubble point. The objective of this study was to evaluate the utility of polyethersulfone membranes (pore size 0.45 µm and bubble point >200 kPa) to extract soil solution from in situ soils and intact soil columns for phosphate analysis. In situ soil solution samplers were constructed from modified reusable polysulfone membrane filter holders equipped with polyethersulfone membranes (47 mm diameter). A -10 kPa vacuum was maintained in the samplers, which enabled soil solution collection at soil water potentials of 0 to -4 kPa in loamy sand, 0 to -10 kPa in sandy loam, and 0 to -12 kPa in sandy clay loam soils. In a laboratory study, soil solution samplers continued to hold a vacuum to -77 kPa soil water potential. Soil solution samplers were further evaluated in a field study at 45-, 90-, and 135-cm depths in two soils. Samplers operated with relatively few difficulties for the first 12 months of field evaluation. Membranes apparently dried during periods of low soil water potential but increases in soil moisture were sufficient to rewet the membrane. Sampler failures in the field increased during 13–18 months because aged vacuum tubing and root interferences with samplers at 45 cm. Improvements in sampler design may improve the durability for implementation in long-term field experiments. Membrane filters worked near flawlessly to maintain unsaturated conditions in intact soil columns. The filter units facilitated easy collection of soil water from the intact soil columns without altering the chemical composition of the percolate. [ABSTRACT FROM AUTHOR]