Browsing by Author "Dhital, Sulochana"

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    Effect of Seed Distribution and Population on Maize (Zea mays L.) Grain Yield
    (International Journal of Agronomy, 2014) Chim, Bee Khim; Omara, Peter; Macnack, Natasha; Mullock, Jeremiah; Dhital, Sulochana; Raun, William
    Maize planting is normally accomplished by hand in the developing world where two or more seeds are placed per hill with a heterogeneous plant spacing and density. To understand the interaction between seed distribution and distance between hills, experiments were established in 2012 and 2013 at Lake Carl Blackwell (LCB) and EfawAgronomy Research Stations, near Stillwater, OK. A randomized complete block design was used with three replications and 9 treatments and a factorial treatment structure of 1, 2, and 3 seeds per hill using interrow spacing of 0.16, 0.32, and 0.48m. Data for normalized difference vegetation index (NDVI), intercepted photosynthetically active radiation (IPAR), grain yield, and grain N uptake were collected. Results showed that, on average, NDVI and IPAR increased with number of seeds per hill and decreased with increasing plant spacing. In three of four site-years, planting 1 or 2 seeds per hill, 0.16m apart, increased grain yield and N uptake. Over sites, planting 1 seed, every 0.16m, increased yields by an average of 1.15Mgha−1 (range: 0.33 to 2.46Mg ha−1) when compared to the farmer practice of placing 2 to 3 seeds per hill, every 0.48m.
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    In-Season Application of Nitrogen and Sulfur in Winter Wheat
    (Agrosystems, Geosciences & Environment,, 2019) Dhillon, Jagmandeep; Dhital, Sulochana; Lynch, Tyler; Figueiredo, Bruno; Omara, Peter; Raun, W. R.
    Decreased atmospheric S deposition in the past 20 yr has led to increased S fertilizer consumption in winter wheat (Triticum aestivum L.). Producers often apply S without any soil test information. Experiments were conducted at Lahoma, Lake Carl Blackwell, and Perkins, OK (2011–2013) to assess the effect of N and S applied preplant and foliar on grain yield and grain N for winter wheat. In 2011–2012, urea ammonium nitrate (UAN) was applied preplant at rates of 40 and 80 kg N ha-1 additionally; UAN and urea-triazone (NSURE) were foliar-applied at rates of 10 and 20 kg N ha-1. Sulfur was foliar-applied as gypsum (CaSO4×2H2O) at 6 kg S ha-1. In 2013, trials were altered to apply 40 kg N ha-1 as UAN preplant, and 20 kg N ha-1 foliar-applied. Gypsum rates were adjusted at 0, 3, and 6 kg S ha-1 preplant, and S (MAX-IN-S) at 3 and 6 kg S ha-1 was foliar-applied. Sulfur did not increase grain yield or grain N concentration at any site. The interaction between foliar S and N and preplant S and N was not significant. Sulfur fertilizer application is less likely to benefit this region unless low levels of soil test S are identified before planting. Use of recommended soiltesting guides are encouraged. Although S applications are encouraged commercially, no response was observed in these trials, and all were on sites where soil organic carbon was low (<8.5 g kg-1), where the possibility of seeing S deficiency was greater.