Matthew Rhine

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.

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.

Measuring Soil and Tissue Potassium with a Portable Ion-Specific Electrode in Cotton

ABSTRACT Most laboratories make potassium (K) fertilizer recommendations based on field research calibrated with soil K from atomic absorption spectroscopy, flame emission spectroscopy, or inductively coupled plasma mass spectrometry. Information is needed to interpret readings from K+ meters on cotton. The objective was to compare soil and cotton plant sap potassium content from a Laqua Twin™ K+ meter to results from standard tests. Aluminum sulfate solution was used with the meter to extract K from 10 soil samples from the North America Proficiency Testing program. A linear relationship (R2 = 0.86) was found between K measured with a K+ meter and K measured with 138 labs using ammonium acetate or Mehlich-3. Using a factor of 1.4754 to adjust readings, fertilizer recommendations with the K+ meter were similar to results from atomic absorption spectroscopy. A linear relationship was found between petiole K measured in the lab and petiole sap measured with the K+ meter.

Soil Testing Bray-1 Phosphorus with Non-Reagent Grade Hydrochloric and Sulfuric Acids

ABSTRACT Portable instruments have reduced on-site testing costs for soil pH and potassium in isolated locations. Acids could not be shipped to a remote Africa field laboratory. Bray-1 phosphorus (P) testing is difficult because hydrochloric (HCl) is required in the extraction solution and sulfuric acid (H2SO4) is used in color development stock solutions. Muriatic HCl acid and battery H2SO4 were available in a local stores. The objectives of this study were to evaluate the accuracy of P soil testing using diluted, non-reagent HCl for making modified Bray1-P extractant and non-reagent H2SO4 for color development. Experiment 1 was conducted with soil samples from fields using Sunnyside™ and Klean Strip™ HCl muriatic acids. Soil samples extracted with diluted reagent HCl were closely related to P results using diluted Klean Strip (R2 = 0.96) and Sunnyside (R2 = 0.84) HCl. In Experiment 2, two commercial brands of H2SO4 acid used to refill car battery cells were evaluated. Test results suggested that the battery H2SO4 acids are not suitable for making color development solution. In Experiment 3, a small battery powered spectrometer for P testing aquarium water was calibrated for soils. Samples from the Soil Science Society of America –North American Proficiency Testing program (NAPT) were tested with the meter and non-reagent HCl. Fiske-Subbarrow reducing agent and HCl were used in a variation procedure which does not require H2SO4 for color development. Eight of 10 samples tested proficient based on NAPT limits (2.5 x Median Absolute Deviation).

Sweet sorghum [Sorghum bicolor (L.) Moench] biomass production for biofuel and the effects of soil types and nitrogen fertilization.

This research aimed to determine the optimum nitrogen fertilization rate on three soils for producing biomass sweet sorghum (Sorghum bicolor cultivar M81E) and corn (Zea mays cultivar P33N58) grain yield and to compare their responses. The research was conducted in Missouri in rotations with soybean, cotton, and corn. Seven rates of nitrogen (N) were applied. Sweet sorghum dry biomass varied between 11 and 27.5 Mg ha−1) depending on year, soil type, and N rate. Nitrogen fertilization on the silt and sandy loam soils had no effect (P > 0.05) on sweet sorghum yield grown after cotton and soybean. However, yield increased in the clay soil. Corn grain yielded from 1.3 to 12.9 Mg ha−1, and 179 to 224 kg N ha−1 was required for maximum yield. Increasing biomass yield required N application on clay but not on silt loam and sandy loam in rotations with soybean or cotton.