Brian H. Marsh

Soybean Response to Row Spacing and Seeding Rates in Northeast Kansas

Soybean is a major crop in northeast Kansas and plays an important role in summer row-crop rotations. Since the early 1980’s, planting soybeans in narrow rows (10 in or less) has become popular and is used for approximately 50% of the soybeans in the region. Row spacing and seeding recommendations generally are developed from results of field experiments and local experience. Kansas producers typically plant between 130,000 and 180,000 seeds/a with 30-in rows and increase seeding rates by approximately 10 to 25% with narrow rows. Yields vary tremendously depending on soil and environmental conditions, with yield potential being 20 to 25 bu/a in some locations and 50 to 60 bu/a in others. This study was designed to determine the influence of environment on optimum row spacing and seeding rates for soybeans in northeast Kansas.

Low-pressure drip system in reduced tillage cotton.

Research has shown the soil and water conservation advantages of subsurface drip irrigation. Low-pressure drip system (LPS) technology has shown a high potential for economically improving application efficiency of irrigation systems under sandy soil conditions in areas where water is scarce and/or expensive. Energy costs are reduced as less than 70 grams per square cm is needed for system operation. The low-pressure system is installed just below the soil surface, it operates at very low flow and pressure, and it can stay on for longer periods of time without generating runoff or deep percolation. This study is designed to assess LPS under a reduced tillage system without the use of any other irrigation method for stand establishment. This combines the benefits of increased water use efficiency and lower energy costs for improved irrigation efficiency and fewer tillage operations resulting in lower production costs and less airborne dust. Since the drip tape was installed two years ago, only 3 cultivation passes have been made. No major tillage operations, the kind that generate lots of dust, have been performed. LPS water usage was 15% less than furrow irrigation and yields of cotton (Gossypium hirsutum) and blackeye beans (Vigna unguiculata) were comparable to yields from furrow irrigation. This system does present some challenges in stand establishment on very sandy soils and with weed control, which continue to be investigated. Herbicides requiring incorporation were not used. Weeds can be controlled in cotton using glyphosate and other herbicides. Fewer chemical weed control options are available for blackeye beans. The LPS technology has many potential technical, energy and economic advantages over standard drip and subsurface drip irrigation.

Response of Acala Cotton to Nitrogen Rates in the San Joaquin Valley of California

The responses of Acala cotton (Gossypium hirsutum L.) in California to a range of applied nitrogen (N) treatments were investigated in a 5-year, multisite experiment. The experiment’s goals were to identify crop growth and yield responses to applied N and provide information to better assess the utility of soil residual N estimates in improving fertilizer management. Baseline fertilizer application rates for the lowest applied N treatments were based on residual soil nitrate-N (NO3-N) levels determined on soil samples from the upper 0.6 m of the soil collected prior to spring N fertilization and within 1 week postplanting each year. Results have shown positive cotton lint yield responses to increases in applied N across the 56 to 224 kg N/ha range in only 41% (16 out of 39) of test sites. Soil NO3-N monitoring to a depth of 2.4 m in the spring (after planting) and fall (postharvest) indicate most changes in soil NO3 occur within the upper 1.2 m of soil. However, some sites (those most prone to leaching losses of soluble nutrients) also exhibited net increases in soil NO3-N in the 1.2- to 2.4-m depth zone when comparing planting time vs. postharvest data. The lack of yield responses and soil NO3-N accumulations at some sites indicate that more efforts should be put into identifying the amount of plant N requirements that can be met from residual soil N, rather than solely from fertilizer N applications.

Forage yield and soilborne mosaic virus resistance of several varieties of rye, triticale, and wheat

Winter annuals such as wheat, rye, and triticale often are used for winter grazing and spring ensilage in Kansas. Soilborne mosaic virus (SBMV) can be a serious problem in the eastern half of the state in any year. Ratings of wheat variety resistance to SBMV are updated each year, but data regarding the resistance of rye and triticale varieties to SBMV are scarce. This study was initiated to evaluate several varieties of rye (Secale cereale L.) and triticale (X Triticosecale Wittmack) for their forage production and resistance to SBMV in comparison to resistant and susceptible wheat varieties.