8 pp. / Wheat and barley are often planted later than optimum due to the timing of the previous crop or to reduce the risk of frost damage. It may be possible to partially compensate for lower yield potential of late plantings by increasing water and nitrogen rates beyond what would have an effect at more optimal plantings. The objective of this study is to evaluate the effects of nitrogen and water rates on late planted wheat and barley. A trial testing water and nitrogen rates for small grains planted late and at the optimal time was established at the Maricopa Ag Center. The experimental design was a split-split plot with main plots as input levels of water and nitrogen (low, medium, and high), subplots as varieties (Tiburon durum and Chico barley), sub-subplots as planting dates (15 December 2015 and 1 February 2016, and 3 replications. In this study, higher levels on inputs of water and nitrogen did not increase yield at later planting dates as we hypothesized. In fact, the highest yields were obtained at medium inputs of water and nitrogen regardless of planting date. The yields of the later planting date were not depressed as we expected due to unusually mild temperatures later in the spring which favored a later planting date this season.

6 pp. / Wheat is commonly grown as a dual purpose crop especially in the Southern Great Plains where the forage is grazed then allowed to mature into a grain crop. In Arizona, clipping a crop planted in October may increase tillering and grain yield. A trial was conducted at the Maricopa Ag Center where various small grain varieties were planted on October 12, 2015, cut for forage on January 10, 2016, and allowed to go to grain and compared with the same varieties planted on December 3, 2016 and not cut for forage. No differences in grain yield due to planting date and clipping were detected. However, the October 12 planting with clipping had larger kernels, greater grain protein, and higher stem density. The income from the sale of the forage was $99/acre based a yield of 2639 lb/acre and a forage value of $75/ton. The added cost per acre to produce this forage included $29 for water (6.27 inches of water at $55/acre-ft) plus $34 for fertilizer (50 lb N/acre of urea at $433/ton). Therefore, even though grain yield was not increased by planting early and clipping, a net increase in revenue of $36/acre was realized from the sale of the forage.

Experiments were conducted to evaluate the most profitable and effective management practices for non-irrigated soybean production. Common production practices were compared side by side to evaluate yield response and economic returns. Combinations of row spacings and planting dates were evaluated to determine interactions between the two factors and also the effects on yield. Lastly, the effectiveness of various iron sources was examined in iron deficiency chlorosis (IDC) susceptible soybeans when applied foliar, inurrow at planting, and a split application. These data suggest that in non-irrigated soybeans, “low input management” practices do not maximize yields, but can be more profitable, depending on soybean market price and input costs, when compared to “full management”. Results also reveal that no interaction between row spacing and planting date occurred with respect to soybean yield. However, planting date did influence soybean yield with the earlier planting dates, mid-April, and mid-May providing the greatest yield. When examining row spacing, soybean grown on rows spaced 38.10 cm apart resulted in greater yield when compared to those grown on 96.52 cm rows. The iron product that consistently provided the greatest visual reduction of IDC symptoms was Sequestar 6% EDDHA chelate applied at 0.20 and 0.27 kg ai ha-1. This treatment was only effective when applied inurrow at planting. However, it was found that soybean yield was not influenced by any iron product or application timing, indicating that visual symptoms of IDC may be managed, but that the visual reduction in symptoms does not translate into yield.

High tunnels have been used for many years worldwide. However, there has been limited research about use of high tunnel technology in the southeastern United States and its popularity has recently increased in Mississippi. A planting date study of 'Roma'' tomato, 'Legend' tomato, 'Ichiban' eggplant, 'Sweet Banana' pepper, ‘Benary’s Giant’ zinnia and ‘Potomac Red’ snapdragon was conducted in spring 2010 in three high tunnels in Starkville, Mississippi. Results showed for most cultivars (tomatoes, eggplant and pepper) a 12 Mar. 2010 planting date did not differ in marketable yield from planting on 2 Apr. 2010. In 2011, a fertilizer study on Encore lettuce mix and Ovation green mix was conducted both in high tunnel and in the field. Results indicated there was no effect of vermicompost tea or fertilizer treatments on yields of salad mixes.

3 pp. / Production practices for grain sorghum are discussed including hybrid selection, planting date, seeding rate, row configuration, irrigation, fertilization, pest control, and harvesting.

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.

3 pp. / The influence of crop species, seed size, seed viability, seed depth,irrigation practices,stand establishment and uniformity, seeding equipment, planting date, crop variety, and planting configuration on optimum seeding rate for small grains is discussed.

Doctor of Philosophy / Department of Agronomy / Nathan O. Nelson / Augustine K. Obour / Emerging sustainability issues with summer-fallow period has prompted producers to identify fallow replacement crops in wheat (Triticum aestivum) production systems. Camelina [Camelina sativa (L.) Crantz] has been identified as a potential fallow replacement crop in the semiarid Great Plains. Camelina has uses in animal and human nutrition, biofuel production, and bio-based products. Three field experiments were conducted to develop production recommendations for camelina in wheat production systems in the semiarid Great Plains. In the first study, three camelina cultivars were evaluated in mid-March (March 17, 2014; March 18, 2015), early-April (April 3, 2013; April 1, 2014 and 2015), and mid-April (April 16, 2013; April 15, 2014 and 2015) at Hays, KS. Findings from this study showed delaying camelina planting until early- or mid-April resulted in 34% increase in seed yield. Planting date affected oil concentration, saturated fatty acids (SFA), monounsaturated fatty acids (MUFA), polyunsaturated fatty acids (PUFA), and linolenic acid concentration. The concentrations of SFA, MUFA, PUFA, linoleic acid, and linolenic acid were also different among cultivars. A second study was conducted to evaluate the response of camelina to nitrogen (N), and sulfur (S) fertilizer application. Nitrogen rates (0, 22, 45 and 90 kg ha⁻¹), and S rates (0 and 20 kg ha⁻¹) were applied in a randomized complete block design with a split-plot arrangement. The main plots were S application rates and the subplot factor was N rates. Sulfur application did not affect seed yield, oil, protein, or seed nutrient concentration. The agronomic optimum N rate was 49 kg N ha⁻¹, however, the economic optimum N rate ranged from 25 to 31 kg N ha⁻¹ based on current N fertilizer cost, and camelina seed price. Nitrogen application had no effect on SFA, MUFA, and PUFA. Moderate N application increased seed calcium (Ca) concentration, whereas higher N rate increased zinc (Zn), and manganese (Mn) concentration in the seed. There was a general negative relation between N application with copper (Cu), and molybdenum (Mo) in camelina seed. Our study shows that camelina needed to be applied with a minimum of 25 kg N ha⁻¹ for optimum production. A third study investigated effects of crop rotation on crop yield, soil water, soil CO₂ flux, and soil health in wheat-camelina rotation systems. Rotation systems in this study were wheat-fallow (W-F), wheat-sorghum (Sorghum bicolor) -fallow (W-S-F), wheat-spring camelina (W-SC), and wheat-sorghum-spring camelina (W-S-SC). Crop rotation had no effect on sorghum grain yield. However, winter wheat yield decreased by 15% when fallow was replaced by camelina in the rotation system. Camelina yield in W-SC was 2-fold greater than that in W-S-SC. Soil water content in the more intensified rotations were less than rotations with fallow, irrespective of sampling period. Soil pH, phosphorus (P), and total nitrogen (TN) were not different among rotation systems. Nonetheless, soil profile N, soil organic carbon (SOC), microbial biomass carbon and N (MBC and MBN), and potentially mineralizable nitrogen (PMN) were different among rotation systems. Soil particle aggregation increased with increasing cropping intensity. This suggests improved soil structure with cropping intensification.

3 pp. / Originally published: 2009 / Production practices for grain sorghum are discussed including hybrid selection, planting date, seeding rate, row configuration, irrigation, fertilization, pest control, and harvesting. Grain sorghum (milo) is a warm season, annual grain crop. It is more resistant to salt, drought, and heat stress than most other crops. Nevertheless, highest yields are obtained when stresses are minimized. Revised 10/2016. Originally published 06/2009.