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Drought and heavier spring storms from climate change will increase crop water stress and affect productivity. A study was conducted to determine whether supplemental irrigation on fine-textured soils with recycled drainage and surface runoff water, combined with nitrogen (N) management, could mitigate these effects. This study was set as a randomized complete block design in a split-plot arrangement with three replicates. The main plots, which were individually drained, corresponded to three water management strategies (full irrigation, limited irrigation, and rainfed), and the subplots corresponded to six N rates (0, 90, 134, 179, 224, and 269 kg/ha) in the corn phase of the rotation. In the soybean phase, the same water management strategies were uniformly applied across the subplots. Irrigation and drainage water, volumetric soil water content (SWC), and grain yield data were collected. The full irrigation significantly increased the SWC in the top 60 cm of the soil across crops during the driest year, where it increased by an average of 30% compared with the rainfed conditions. The limited irrigation increased the SWC in the top 20 cm only for the soybean during the driest year, where it increased by as much as 25%. As a result, the supplemental irrigation prevented yield reduction in one year. While the irrigation alone did not significantly affect the grain yield of either crop, the irrigation × N interaction for the corn was consistently significant, which suggests that the N effectively enhanced the corn productivity. The results suggest that reusing drainage water could be a valuable practice for reducing the effects of limited soil water on crops in fine-textured soils. [ABSTRACT FROM AUTHOR]

Due to the environmental consequences of annual‐dominated cropping systems, there is an increasing need to identify agronomic strategies that incorporate perennial crops. One strategy for increasing perennial cover is through the targeted use of annually harvested perennial food and bioproduct crops in buffer strips, which has the potential to create new revenue streams for farmers and substantially mitigate agricultural nutrient pollution from conventional cropping systems. As buffers are typically installed on marginal land, it is critical to understand how landscape position influences the success of perennial crops. The objectives of this study were to determine the relatively early influence of landscape position on the productivity of a variety of perennial crops and their subsequent soil nutrients and soil water storing capabilities. In this experiment, nine perennial (alfalfa, alsike clover, indiangrass, switchgrass, big bluestem, prairie cordgrass, intermediate wheatgrass, high‐diversity polyculture, low‐diversity polyculture) and two annual (corn, soybean) crops were planted across two landscape positions (hillslope and deposition). Plant biomass, plant tissue nitrogen, soil moisture, and soil NO3‐N and NH4‐N were measured and compared at two different locations in Minnesota. Overall, the polyculture mixes, and to some extent intermediate wheatgrass, performed the best with respect to biomass production while also providing ecosystem services across most soil by landscape position combinations tested in this study. However, there were some important findings specific to each soil and landscape position combination, mainly oriented toward biomass production. We also observed temporal patterns in soil moisture and depth‐related patterns in soil N reductions. This study presents an opportunity to optimize the use of perennial crops on marginal agricultural lands for improved environmental and economic benefit. [ABSTRACT FROM AUTHOR]

Cover cropping practices are being researched to reduce artificial subsurface drainage nitrate-nitrogen (nitrate-N) losses from agricultural lands in the upper Mississippi watershed. A soil-plant-atmosphere simulation model, RyeGro, was developed to quantify the influence of a winter cereal rye cover crop on nitrate-N losses given climatic variability in the region. This paper describes the hydrology and nitrogen cycle submodels of RyeGro, which was developed with a low level of complexity and conceptualizes the soil profile as three soil layers. The model was calibrated with data from a three-year rye cover crop field study conducted at Lamberton, Minnesota, and validated with data from a previous study. During model calibration, field subsurface drainage nitrate-N loadings were predicted within 0.2, 0, and 1.6 kg N [ha.sup.-1] (1, 0, and -3%) of measured loadings for the corn-soybean treatment and within 1.2, 0, and 1.6 kg N [ha.sup.-1] (11, 0, and 3%) of measured loadings for the corn-rye-soybean treatment. The model validation showed nitrate-N loading differences of ? and 1 k gN [ha.sup.1] (-22 and 4%) for the two years tested. DOI: 10.1061/(ASCE)0733-9437(2007)133:2(90) CE Database subject headings: Subsurface drainage; Nitrogen; Nitrates; Nutrient loads; Computer models; Soil water storage; Crops; Agriculture.

Provides information on a study which developed equipment and protocols for conducting unsaturated solute transport on undisturbed soil blocks. Materials and methods; Results and discussion.