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Soybean (Glycine max L. Merr.) planting date and plant density are agronomic decisions made simultaneously at the beginning of the growing season that can be used to maximize yield and economic return. Research on these basic soybean agronomic decisions must be conducted to support the expansion of soybean production in northern growing regions of the Northern Great Plains (NGP). The objectives of this study were to evaluate the effects of planting dates based on soil temperature on soybean emergence, maturity, and yield for short and long season varieties in Manitoba, and to determine optimum soybean plant density for early to very late planting dates in northern growing regions of the NGP. In the first experiment, calendar date had a greater influence than soil temperature at planting on soybean yield. Soybean yield declined with later planting rather than increasing soil temperature at planting. The earliest planting dates resulted in the greatest soybean yields. In the second experiment, soybean yield-density relationships were responsive to planting date. Yield-density relationships formed early/mid (May 4 to 26) and late/very late (June 2 to 23) planting date groups for combined site years. Early/mid planting dates resulted in greater maximum yields. According to the yield-density model, true yield maximization did not occur for any planting dates and site years within the range of plant densities tested in this field study. Soybean economic optimum seed densities (EOSDs) were much lower than predicted plant densities that maximized yield. Soybean EOSDs were identified as 492,000 and 314,000 seeds ha-1 by marginal cost analysis for early/mid and late/very late planting, respectfully. These values were sensitive to changes in soybean grain price and seed cost. Thus, growers need to adjust EOSDs for changes in price and cost. A combined analysis of soybean yields from both experiments using similar target plant densities determined that a significant negative linear relationship existed between soybean yield and planting date. The greatest soybean yields resulted from early planting and declined by 16 kg ha-1 for each one-day delay in planting from Apr 27 to June 16. However, yield responses varied among site years. The overall recommendation from this study would be to plant soybeans during the month of May at a profit-maximizing seed density, accounting for fluctuating grain price and seed cost. / May 2017

Master of Science / Department of Agronomy / Scott A. Staggenborg / In Kansas, productivity of grain sorghum [Sorghum bicolor (L.) Moench] is affected by weather conditions at planting and during pollination. Planting date management and selection of hybrid maturity group can help to avoid severe environmental stresses during these sensitive stages. The hypothesis of the study was that late May planting improves grain sorghum yield, growth and development compared with late June planting. The objectives of this research were to investigate the influence of planting dates on growth, development, and yield of different grain sorghum hybrids, and to determine the optimal planting date and hybrid combination for maximum biomass and grains production. Three sorghum hybrids (early, medium , and late maturing) were planted in late May and late June without irrigation in Kansas at Manhattan/Ashland Bottom Research Station, and Hutchinson in 2010; and at Manhattan/North Farm and Hutchinson in 2011. Data on leaf area index, dry matter production, harvest index, yield and yield components were collected. Grain yield and yield components were influenced by planting date depending on environmental conditions. At Manhattan (2010), greater grain yield, number of heads per plant, harvest index, and leaf-area were obtained with late-June planting compared with late May planting, while at Hutchinson (2010) greater yield was obtained with late May planting for all hybrids. The yield component most affected at Hutchinson was the number of kernels panicle-1 and plant density. Late-May planting was favorable for late maturing hybrid (P84G62) in all locations. However, the yield of early maturing hybrid (DKS 28-05) and medium maturing hybrid (DKS 37-07) was less affected by delayed planting. The effects of planting dates on growth, development, and yield of grain sorghum hybrids were found to be variable among hybrid maturity groups and locations.

Thesis (M.S.)--Oregon State University, 2008. / Printout. Includes bibliographical references. Also available on the World Wide Web.

M. Tech. Agriculture / The high nutritional value of pigeon pea explains its importance in the diet of smallholder farmers in Africa. Pigeon pea grain is used in many forms. Pigeon pea is consumed mainly as dhal (split-grain) by the Asian community in South Africa, while the African population uses the dry grain. The leaves and stems of pigeonpea serve as an excellent feed for livestock or as fuel wood. Low soil N often limits plant growth and symbiotic N2-fixation offers opportunity to overcome low soil N levels for increased crop yield. However, N is also known to be the most commonly deficient nutrient in soils. Biological N2-fixation is therefore a cheaper source of N for improving crop yields. Because symbiotic systems contribute great amounts of N input into natural and agricultural ecosystems, legume N2-fixation is considered cheaper source of N for poor farmers. It is also more sustainable and environmentally friendly compared to fertilizer N. Nitrogen-fixing microorganisms therefore provide an alternative to inorganic fertilisers which are expensive and not easily accessible to poor rural farmers. This study evaluated plant growth and symbiotic performance C accumulation, P nutrition and grain yield/quality in ratooned pigeon pea (Cajanus cajan L. Millspaugh) genotypes obtained from international crops research institute for semi-arid tropics.

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This item was digitized as part of the Million Books Project led by Carnegie Mellon University and supported by grants from the National Science Foundation (NSF). Cornell University coordinated the participation of land-grant and agricultural libraries in providing historical agricultural information for the digitization project; the University of Arizona Libraries, the College of Agriculture and Life Sciences, and the Office of Arid Lands Studies collaborated in the selection and provision of material for the digitization project.

Smallholder tree planting is a pathway recognized within Forest Transition Theory (FTT), but its contributing factors are not fully explored at the household level. This study examines the effect of socio-economic and biophysical characteristics, access to extension services, land tenure, labour availability, and attitudes toward tree cover on smallholder planting and willingness to plant for environmental and economic purposes at the household level. Data was collected from 146 households in Mocoties, Merida, Venezuela. Logistic models revealed that area of property, area of productive land, presence of natural sources of water, gender of respondent, number of generations that have farmed the property, income, percent income from farming activities, land title, harvest rights, labour availability and attitudes toward tree cover have significant influence on smallholder’s tree planting and willingness to plant. Future research needs to focus on factors that affect environmentally motivated smallholder tree planting where fewer significant variables were found.