M.S.

Increased demand for barley has changed the proportion of crops grown in Virginia and the Mid-Atlantic USA. Winter wheat is the predominant small grain crop, but barley can be a direct substitute, although much less of it is grown. Soybean is grown full-season and double-cropped after both small grains. Historically, wheat was the primary small grain in the soybean double-crop rotation because of its greater profitability. The barley-soybean cropping system is not a new concept in the region, but the literature is outdated. New agronomic and economic data that directly compares full-season soybean, barley-soybean, and wheat-soybean systems using modern cultivars and management practices is needed. The objectives of this research were to: i) determine soybean yield and compare cropping system profitability of the three cropping systems; ii) perform a breakeven sensitivity analysis of the three cropping systems; and iii) determine the effect of planting date and previous winter crop on soybean yield and yield components. Soybean grown after barley yielded more than full-season soybean in two of six locations and more than soybean double-cropped after wheat in three of six locations. Net returns for the barley-soybean system were the greatest. These data indicate that soybean double-cropped after barley has the potential to yield equal to or greater than full-season soybean or double-cropped soybean following wheat, but its relative yield is very dependent on growing conditions. The profitability comparison indicated that the barley-soybean cropping system was generally more profitable than the full-season soybean and double-cropped wheat-soybean systems. This conclusion was supported by the breakeven sensitivity analysis, but remains dependent on prices that have been extremely volatile in recent years. In another study, soybean yields declined with planting date at two of four locations in 2009, a year that late-season rainfall enabled later-planted soybean to yield more than expected. In 2010, soybean yield decline was affected by the delay in planting date at both locations. Winter grain did not affect soybean yield in either year. Yield component data reinforced these results and indicated that the lower seed yield in the later planting dates was due primarily to a decrease in the number of pods. / Master of Science

Studies have shown that significant amounts of nitrate-N is leached beyond root zones of annual crops while small amounts of nitrate-N is leached beyond the root zones of perennial forage grasses. This study investigated short-term ammonium-N persistence and root nitrogen content of annual crop and perennial forage grasses following application of pig manure to a sandy loam soil at Carman, Manitoba. Results showed that ammonium-N in liquid pig manure (LPM) amended treatment peaked four days after manure application (DAM) in perennial cropping system (PCS; 50 - 74 kg ha-1) and annual cropping system (ACS; 18 - 29 kg ha-1) in 2014 and 2015. Ammonium-N persisted up to 7 DAM in LPM amended PCS, but did not persist beyond 4 DAM in LPM amended ACS. Ammonium-N measured in solid pig manure (SPM) amended ACS and PCS was low throughout the sampling days in both years. There was a greater percentage increase in accumulation of nitrate-N at 15 - 30 cm soil depth of LPM and SPM amended ACS than PCS. In both years, dry weight below-ground plant biomass ranged from 5,258 to 9,627 kg ha-1 at 0 - 60 cm depth in PCS while that of ACS ranged from 1,088 to 1,456 kg ha-1. Also, root N content in PCS ranged from 43 to 118 kg N ha-1 in both years while that of ACS ranged from 9 to 20 kg N ha-1. In conclusion, ammonium-N persisted longer in PCS than ACS in the short-term and total plant N was greater in PCS than ACS. Greater total plant N in PCS than ACS was mainly due to its greater root N content rather than above-ground N uptake. The order of magnitude of the difference in root N content (34 to 98 kg N ha-1) between ACS and PCS was sufficient to account for the 20 to 60 kg N/ha of nitrate-N leached in ACS in previous study at the same site. / October 2016

ABSTRACT Effects of Compost, Legume Cover Cropping and Vermicompost Extract Foliar Applications on Nutrition and Yield of Washington Navel Oranges William Payton Carling An experiment was conducted to test the effects of four treatments on Washington navel orange (Citrus sinensis) trees in regards to nutrient content of the leaves and fruit, soil nutrient content and properties, and fruit yield. The four treatments included: compost (C) and vermicompost extract foliar (VEF) applications, legume cover cropping (LCC) and VEF applications, VEF applications, and a control. The treatments were implemented from February 2010 to April 2011 and sampling occurred in May 2011. Fruit Growers Laboratory, Inc. (FGL) conducted the soil, leaf, and fruit analyses. The test site was located in San Isidro, Baja California Sur, Mexico. The compost used was made onsite with livestock manure, carbon-based farm waste, and water, and applied around the drip-lines of 8 WNO trees once every two months. The vermicompost and vermicompost extract was made onsite by introducing red wiggler worms (Eisenia fetida) into horse manure, allowing 1 month for casting content to build up, and collecting the extract as water was filtered through the material. Vermicompost extract was applied using a backpack foliar sprayer on 8 WNO trees twice a month. The legume cover crop treatment consisted of two plantings at a rate of approximately 72 seeds per square foot around the drip-lines of 8 WNO trees. Black-eyed peas (Vigna unguiclata) were planted in April 2010 and minimally incorporated using a hoe and shovel in August 2010. Fababeans (Vicia faba) and dry peas (Pisum sativum) were planted in January 2011 and minimally incorporated into the soil in March 2011. WNO leaf and soil analyses were compared to FGL optimum ranges. The C+VEF treatment showed trends of increased soil and leaf nitrogen, phosphorus, potassium, calcium, zinc, and copper levels and improved soil properties by raising soil organic matter percentage, saturation percentage, and moisture percentage. The control treatment had low or deficient values in these nutrients and soil properties. The LCC+VEF treatment increased nitrogen in the soil and leaf content but decreased organic matter percentage. The VEF treatment increased nitrogen and potassium content in the leaf but increased sodium beyond FGL optimum range. The C+VEF treatment had the highest yield and the greatest amount of nutrients removed as a result of yield. The C+VEF treatment had more available nutrients in the soil for WNO tree uptake and future crops.

Pulse crops included in a crop rotation can reduce nitrogen (N) requirements via biological N2 fixation (BNF) and provide greater carbon (C) inputs to soil than non-pulse crops in rotation. The goal of this research was to estimate the BNF and C input to soil by various pulse crops (chickpea, lentil and field pea) grown in rotation with pulse crops and non-pulse crops. Soil cores from three crop rotations (chickpea-wheat, lentil-wheat and pea-wheat) were collected from Swift Current, SK. Additional soil cores from two rotations (canola-wheat and wheat-canola) were extracted from a field used for commercial cropping in Central Butte, SK. The 15N dilution method and continuous labelling with depleted 13CO2 were used to estimate BNF and 13C input to soil by pulse crops grown in a greenhouse. The continuous labelling with depleted 13CO2 was effective in depleting 13C in plants. The movement of 13C from plant to soil C pools via rhizodeposition was also observed. However, an accurate amount of 13C transferred was not measurable. Different pulse crop performed differently in rotation. Pea had the greatest amount of BNF and produced the most residue-C (pods, stems, leaves and roots) compared to chickpea and lentil. The crop grown in the first year of the three-year rotation also influenced the pulse crops grown in the third year of the rotation. Cropping the same first year and third year pulse crop in rotation (chickpea-wheat-chickpea and lentil-wheat-lentil) performed better than growing different first year and third year pulse crops in rotation (pea-wheat-chickpea and pea-wheat-lentil). Pulse crops grown immediately after wheat yielded better and fixed more N than those after canola. Growing a pulse crop after canola is not recommended in this soil zone.

Doctor of Philosophy / Department of Agronomy / Kraig L. Roozeboom / Previous research has revealed that winter wheat (Triticum aestivum L.) yields are often reduced following grain sorghum [Sorghum bicolor (L.) Moench] compared to wheat after other summer crops. The objectives of the study were to: (a) evaluate grain sorghum residue management strategies to improve the performance of a following winter wheat crop in no-till systems; (b) determine grain sorghum hybrid characteristics that facilitate planting wheat following grain sorghum, and identify winter wheat cultivars that are suitable for planting after grain sorghum; (c) evaluate effect of environment, sampling time, and grain sorghum hybrid plant pigmentation on phenolic acid concentration in sorghum residues. Experiments were conducted in environments suitable for planting winter wheat following a summer crop. Treatments for objective one were: glyphosate (pre-harvest application, post-harvest, none), residue (removed, chopped, left standing), and nitrogen (34 kg ha⁻¹ applied to residue, none). Treatments for objective two and three were grain sorghum hybrids representing three maturities (early, medium, medium-late) and two plant pigmentations (red, tan), wheat cultivars occupying significant planted acreage and having favorable performance within the region. Wheat yields increased in two environments by 217 and 630 kg ha⁻¹ when glyphosate was applied to the sorghum pre-harvest. Residue chopping or removal either had no effect or a negative effect on wheat yields compared to residue left standing. Nitrogen applied to the sorghum residue increased wheat yields in only one environment. Grain sorghum hybrid characteristics did not influence winter wheat yields in any environment, but winter wheat cultivar did influence grain yields of the winter wheat in three of the four environments. Breakdown of phenolic acids depended on environment. Results for these studies indicate that wheat yield after a grain sorghum crop can be maximized by planting a red-pigmented sorghum hybrid of an early or medium maturity, desiccating the sorghum crop with pre-harvest glyphosate if it can be applied to the sorghum roughly 45 to 50 days before a frost, and with a wheat cultivar that is well suited to no-till planting.

Typescript (photocopy). / Digitized by Kansas Correctional Industries

Typescript (photocopy). / Digitized by Kansas Correctional Industries

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An intercropping study was carried out with three legumes (field beans, cowpeas, and soybeans) and three cereals (sorghum, corn, and pearl millet) in all combinations to define the most appropriate intercropping under near optimum irrigation. The sorghum x soybean intercropping was chosen as the most appropriate for the environment.