Effect of Soybean Plant Populations in a Soybean and Maize Rotation

Abstract

findings that, when available, soil N is the main source of N for soybean growth rather than N fixation (Her-Plant population of soybean [Glycine max (L.) Merr.] may influridge and Brockwell, 1988). Thus, growing soybean can ence the residual N contribution to a cropping system and yield beneresult in a net depletion of soil N (Zapata et al., 1987). fits to following cereals. Field studies were conducted from 1994 to 1996 on a N-depleted Sharpsburg silty clay loam soil at Mead, NE High amounts of N are removed by harvested soybean to: (i) determine soybean yield at different plant populations; (ii) seeds (144 and 169 kg N ha Ϫ1 , Clement et al., 1992; investigate residual N, chlorophyll-N-yield relations, and yield bene-150-200 kg N ha Ϫ1 , Varvel and Peterson, 1992). This fits from these different soybean populations to a following maize 12678. Work supported in part by the Canadian Int. Dev. Agency (CIDA).

Improved Yield and Nitrogen Use Efficiency of Corn following Soybean in Irrigated Sandy Loams

“…Previous research conducted on Rozetta silt loam attributed greater N uptake by C1 to enhanced N availability through soybean root-induced N mineralization and increased biological activity (Vanotti and Bundy, 1995). Similar results were reported by Ennin and Clegg (2001), who found greater N uptake by CS than CC grown on Sharpsburg silty clay loam soils.…”

“…Previous research conducted on irrigated loamy sand or silty loam soils did not find a soybean N contribution to the following corn (Hesterman et al, 1986;Bundy et al, 1993;Ennin and Clegg, 2001) because of NO 3 − -N lost through leaching before it could be recovered by the corn. Angle (1990) documented the greatest mineralized soil-N concentrations following soybean at the surface of a coarse loamy soil in the fall.…”

“…Previous research has reported soybean N credits to the following corn of 30 kg N ha −1 (Ding et al, 1998), 65 kg N ha −1 (Varvel and Wilhelm, 2003), and 75 kg N ha −1 (Blevins et al, 1990). In contrast, others have found that soybean can be an effective N sink; based on the change in soil NO 3 − -N, NO 3 − -N concentrations were reduced 36 kg N ha −1 (Vanotti and Bundy, 1995) and 48 kg N ha −1 (Ennin and Clegg, 2001). Nitrogen credit from the preceding legume is associated with the potential for biological N 2 fixation by legume-Rhizobium symbiosis, which is probably affected by inherent soil chemical and physical properties and seasonal growing conditions.…”

Planting Date, Cultivar, and Seeding Rate Effects on Soybean Production along the Texas Gulf Coast

“…Increasing the seeding rate by 50% did not always result in a significant increase in soybean yield or net returns. Ennin and Clegg (8) reported that plant populations beyond 52,000 plants/acre might not be necessary to maximize yield with MG 3 determinate soybean cultivars. Bello et al (2) also did not find an increase in yield of determinate, semi‐determinate, and indeterminate soybean by doubling plant populations from 154,000 to 300,000 plants/acre.…”

Nitrogen Fertilizer Replacement Value of Soybean for Corn

“…Most but not all land grant universities in the northeastern and Mid-Atlantic states include some adjustment in N guidelines for corn after soybean ( Table 1). Research in the Midwest showed optimum economic N rates are generally lower for corn after soybean than for corn after corn (1,3,6,18,38,49,58,66,67), but potential N fertilizer savings range widely ( Table 2). Studies conducted in New York showed a 60 lb/acre N savings for corn after soybean in 3 of 5 years.…”