Gene Stevens

Yield and nutritional responses to waterlogging of soybean cultivars

Furrow irrigating soybean prior to a large, unexpected rainfall event can reduce nitrogen fixation and crop yield. The objective of this study was to evaluate the tolerance of soybean cultivars to waterlogged alluvial soils. Five cultivars were selected, which showed a range of tolerances to excessive soil water. Flood duration and flood timing experiments were conducted on clay and silt loam soils. Main plots were flooding duration and flood timing and subplots were soybean cultivars. Most cultivars were able to withstand flooding for 48–96 h without crop injury. Cultivars flooded during the V5 growth stage suffered the least amount of yield loss. The greatest yield losses from flooding occurred at the R5 growth stage. Soybean yields from cultivars flooded at R5 were reduced by 20–39% compared to non-flooded checks. Pioneer 94B73 (cv.) had no significant change in yield from flooding for 192 h at any of the three growth stages, compared to non-flooded controls.

Transgenic Biofortification of the Starchy Staple Cassava (Manihot esculenta) Generates a Novel Sink for Protein

Although calorie dense, the starchy, tuberous roots of cassava provide the lowest sources of dietary protein within the major staple food crops (Manihot esculenta Crantz). (Montagnac JA, Davis CR, Tanumihardjo SA. (2009) Compr Rev Food Sci Food Saf 8:181–194). Cassava was genetically modified to express zeolin, a nutritionally balanced storage protein under control of the patatin promoter. Transgenic plants accumulated zeolin within de novo protein bodies localized within the root storage tissues, resulting in total protein levels of 12.5% dry weight within this tissue, a fourfold increase compared to non-transgenic controls. No significant differences were seen for morphological or agronomic characteristics of transgenic and wild type plants in the greenhouse and field trials, but relative to controls, levels of cyanogenic compounds were reduced by up to 55% in both leaf and root tissues of transgenic plants. Data described here represent a proof of concept towards the potential transformation of cassava from a starchy staple, devoid of storage protein, to one capable of supplying inexpensive, plant-based proteins for food, feed and industrial applications.

Juice, sugar, and bagasse response of sweet sorghum (Sorghum bicolor (L.) Moench cv. M81E) to N fertilization and soil type

The objective of this research was to determine the optimum nitrogen fertilizer rate for producing sweet sorghum (a promising biofuel crop) juice, sugar, and bagasse on silt loam, sandy loam, and clay soils in Missouri. Seven nitrogen fertilization rates were applied, ranging from 0 to 134 kg N ha−1. Regardless of the soil and year, the juice content of sweet sorghum stalk averaged 68.8% by weight. The juice yield ranged from 15.2 to 71.1 m3 ha−1. Soil and N rate significantly impacted the juice yield (P < 0.0001). The pH and the density of the juice were not affected by the soil or N. The sugar content (Brix) of the juice varied between 10.7% and 18.9%. N fertilization improved the sugar content of the juice. A negative correlation existed between the sugar concentration and the juice yield. In general, the lowest sugar content was found in the clay soil and the impact of the N fertilization on juice sugar content was most pronounced in that soil. The juice sugar yield ranged between 2 and 9.9 Mg ha−1, with significant differences found between years, N rates, and soils. N fertilization always increased the sugar yield in the clay soil, whereas in loam soil, a significant sugar response was recorded when the sweet sorghum was planted after corn. The average juice water content was 84% by weight. The dry bagasse yield fluctuated between 3.2 and 13.8 Mg ha−1 with significant difference found with N rate, soil, and year. When sweet sorghum was grown after soybean or cotton, its N requirement was less than after a corn crop was grown the previous year. In general, a minimum of 67 kg N ha−1 was required to optimize juice, sugar, and bagasse yield in sweet sorghum.

Experimentation on Cultivation of Rice Irrigated with a Center Pivot System

Rice is the staple food for one half of the world’s population. Consumed mainly by humans rather than fed to livestock, rice is an efficient food for supplying carbohydrates, vitamins, and nutrients in diets. Demographers predict the Earth’s population will increase to nine billion people by 2045 (United Nations, 2004). To keep pace with increased food demand, rice farmers will need higher yields, increased hectares of rice production, and more efficient use of water resources. Unfortunately, traditional rice production uses large amounts of water. Irrigation practices are needed to grow rice with less water and on welldrained soils that are not currently used for traditional flooded rice culture.

Fragiudults genesis involving multiple parent materials in the eastern ozarks of missouri

Situated in the Missouri Ozarks (Central USA), we examined two fragipan-bearing soils developed in loess and cherty dolomite residuum (i) to characterize two Typic Fragiudult pedons formed in loess, possibly colluvial material formed from dolomitic residuum, and dolomitic residuum and (ii) to establish the role that multiple parent materials have in soil profile development. The upper and lower boundaries of the fragipan correspond to lithologic discontinuities separating (i) loess and bioturbated residuum composed of the eluvial-illuvial sequence from colluvial material forming the fragipan and (ii) the fragipan from the underlying dolomitic residuum. Clay illuviation was observed in the fragipan, inferring that weathered soil material from the upper sequum impacted fragipan expression. Iron concentrations change substantially at the parent material transitions, reflecting pedogenic processes and parent material inheritance. Silicon contents do not reflect the presence of the fragipan, and the role of Si as a binding agent responsible for fragipan brittle remains elusive. The upper sequum supports a hydroxy-Al interlayered vermicultite and kaolinite mineralogy, whereas the lower sequum has a smectite and kaolinitic clay mineralogy. It is proposed that the fragipan is a colluvial feature and that hydroconsolidation has contributed to the fragipans properties. The upper sequum is a mixture of loess and residuum that has formed an ochric-argillic horizon sequence and has been welded to the fragipan because of clay illuviation.

Return of aboveground nutrients by switchgrass into the surrounding soil during senescence.

Background: Switchgrass (Panicum virgatum L.) is a crop that holds promise for cellulosic biofuel production. To minimize fertilizer costs, farmers prefer to reduce crop removal of nutrients from the soil when biomass is harvested. The objective of this study was to monitor, from May 2008–November 2009 at Portageville (MO, USA), the nutrient concentration in the soil, switchgrass roots and rhizomes in a 20-year-old switchgrass field. Soil and tissue samples were collected to determine the sink of the nutrients lost in the aboveground biomass during senescence of the plant. Results: Nutrient concentration in switchgrass biomass decreased from July to the end of the season. In general, as switchgrass senesced, the nutrient concentration of the roots did not significantly change, whereas that of the rhizomes increased. Soil test results varied depending on where samples were collected relative to switchgrass root clumps. Generally, soil samples collected from the clump showed the highest evidence of nutrients returning to the soil from the aboveground biomass; however, some of this could be due to root breakage during sampling. Soil ammonium acetate extracted K in the clumps and averaged 218 kg K kg-1 soil in October, compared with 302 mg K kg-1 soil in November. Soil NO3-N content in the clumps in November was 5.5 mg kg-1 soil, compared with 1.5 mg kg-1 soil in October. Conclusion: This study provided evidence of nutrient recycling in the field by switchgrass plants and supports the concept of a reverse flow of nutrients to soil at the end of the season. The harvest of switchgrass late in November will help minimize the nutrient removal and maximize biomass yield.

EFFECT OF NITROGEN TIMING AND RATES ON TILLERING AND YIELD OF NO-TILL WATER-SEEDED RICE

Approximately one-third of the rice (Oryza sativa L.) in the United States is established by aerial application of pre-germinated rice into flooded fields. In the upper Mississippi alluvial region, no-till water-seeded rice farmers apply all of the nitrogen fertilizer on fields after flooding. The objective of a field experiment initiated in 1996 was to determine the optimum timing for making the first N application in this system. Rice seeds (L202 cv.) were broadcast by airplane into an established flood on a Gideon clay loam soil (fine-loamy, mixed, thermic Mollic Fluvaquent) in Missouri. Rice tillering and yield response to six N rates and six application timings were examined in small plots. Urea fertilizer (45.5% N) was broadcast applied at 15, 20, 25, 30, 35, 40 days after seeding (DAS) at the rates of 0, 28, 56, 84, 112, and 140 kg N ha−1. This was followed by two mid-season 28 kg N ha−1 applications on all plots. Two-year results showed that significantly more early tillers and yield were obtained when the first N application was made at 30 to 35 DAS [350 to 430 growing degree days base temperature 10°C (GDD10) after seeding]. Averaged across years and N rates, rice with the first N applied 30 DAS yielded 7817 kg ha−1. Rice receiving the first N applied 15 DAS yielded 5819 kg ha−1. Regression analysis showed that the optimum first N rate for the first N application was 35 DAS at a rate of 101 kg N ha−1.

Analysis of deterministic simulation model performance using non-replicated factorial two-level experiments

Abstract The usefulness of deterministic simulation models has increased in agricultural applications. This increase must be matched with the use of analytical tools that can verify and validate their performance and help interpret their output. Values of model input variables can be selected by the analyst and are analogous to the concept of factors in conventional experiments. However, deterministic models cannot produce independent replications of selected input variables; many statistical analysis procedures cannot therefore be utilized. Consequently, this presentation describes the use of techniques applicable to the analysis of unreplicated, two-level factorial experiments. It is demonstrated that these concepts are a solution to the problem of how to evaluate deterministic simulation model performance and analyse deterministic simulation experiments.

Biomass production and soil nutrient removal by switchgrass grown for biofuel production

With the energy crisis, interest is being focused on biofuel crops such as switchgrass. Efficient production of biomass from switchgrass to produce biofuel can contribute to helping address the energy problems faced by humankind. Research was implemented between 2008 and 2009 in Southeast Missouri, USA, to investigate the potential biomass production from switchgrass (Panicum virgatum cv. Alamo), and to monitor the changes in the uptake of N, P, K, Ca, Mg, Fe, Cu, Zn and Mn in the aboveground switchgrass biomass from May to November, in order to determine the optimum harvest time to produce the highest biomass yield with minimal nutrient removal. The maximum annual biomass production was 22–29.1 Mg ha-1. The date that the maximum biomass was obtained did not coincide with the minimum nutrient removal date. The nutrient uptake was dependant on the date of harvest, with the maximum being reached around July, followed by a significant decrease until the end of the season. During senescence, nutrients moved from the plant to the soil. Late November appeared to be the best date to harvest the switchgrass in order to minimize the nutrient removal and maximize biomass yield.

Chapter 4:Sweet Sorghum as a Biofuel Crop

Sweet sorghum is a C4 grass which is traditionally cultivated for making syrup from the sugars in the stalks. Sweet and grain sorghum are in the same species, Sorghum bicolor(L.) Moench. In optimum conditions, sweet sorghum can grow 4.5 meters tall and produce 45 to 110 Mg of fresh weight biomass per hectare with less N and water than maize. Ethanol can be produced from sweet sorghum stalks by extracting the juice and fermenting the sugars with yeast. Bagasse remaining after extraction can be fed to livestock or converted to useable energy by burning to produce steam for generating electricity, anaerobic digestion to make methane, or reacting with oxygen at high temperature to produce synthetic gas. Sweet sorghum can be grown in most climates. Some cultivars will grow as far north and south as the 45° latitude. It is normally grown as an annual crop. But, in warm climates, a single seed planting can be managed for two or three years by leaving lower stalks and roots at harvest to produce new tillers for the next growing cycle. Rotating sweet sorghum in alternate years with a non-grass crop is an effective management tool for reducing insect, weed, and disease pests. Nitrogen fertilizer can often be reduced when sweet sorghum is planted after a legume crop such as soybean. Most of the sugar for syrup and ethanol from sweet sorghum is currently produced with open pollinating cultivars. Recently, hybrid sweet sorghums with increased sugar content and biomass yield have been developed in India, China, and the United States.