Effects of land preparation and maize cultivar on efficiency of N-fertilizer applied at different times and by different methods in maize—mungbean association using15N

Abstract

A field experiment was conducted using as N-labelled urea on a Reddish Brown Lateritic (Peleustult) soil. Growing two crops on flat land and on soil ridges of 15 cm height produced similar comparative effects from fertilizer on maize. However, fertilizer applied by broadcasting on maize with a 50 cm effective band followed by incorporating was more useful to mungbean than that applied by banding below the cereal seed rows when crops were grown on flat land. The reverse was observed when crops were grown on ridges. It was deduced that the maize cultivar was not likely to affect comparative efficiencies of fertilizer.For fertilizer application at sowing, broadcasting in 50 cm maize effective band followed by incorporating was slightly superior to banding below maize seed rows. Side-dressing of fertilizer to maize at 4 weeks after sowing was superior to application at sowing. Evenlysplit application, at sowing and at 4 weeks after sowing, was either only slightly superior or comparable to non-split application by banding below maize seed rows at sowing, depending on placement method of the first application. Soil moisture status as a possible factor rendering discrepancy in the comparative efficiencies obtained by different authors is discussed.

Nitrogen‐15 evaluation of fertilizer placement at planting for corn production

“…Even when broadcasting was followed by incorporation in the present study to control NH 3 loss, Tables 8 and 9 show that F 15 NUE was almost always lower for the BC treatment than Conceal placement with significance ( p < 0.05) for grain and total aboveground biomass (Sites 1, 3, and 4) or at least one plant part (Sites 2 and 5). These findings are consistent with previous 15 N field trials that show either no significant difference between broadcasting and banding (Cho et al., 1967; Suwanarit et al., 1986) or lower F 15 NUE for broadcasting (Suwanarit et al., 1983). The implication is that the rate of N can be reduced by banding rather than broadcasting fertilizer N at planting, which not only enhances economic profitability for producers but also reduces the risk of adverse environmental consequences.…”

“…than the single (Sites 2 and 3) banding approach, and except for Site 2, occurred for multiple plant parts. These findings differ from what has been reported in previous 15 N studies evaluating starter placement, which are limited to those by Cho et al (1967) and Suwanarit et al (1986). In the study by Cho et al (1967), a significant advantage was observed for 5 × 5 placement relative to broadcasting when NDF 15 F was evaluated early in the growing season, but this benefit subsequently disappeared presumably because of isotopic dilution by unlabeled N derived from a soil high in organic matter.…”

“…one plant part (Sites 2 and 5). These findings are consistent with previous 15 N field trials that show either no significant difference between broadcasting and banding (Cho et al, 1967;Suwanarit et al, 1986) or lower F 15 NUE for broadcasting (Suwanarit et al, 1983). The implication is that the rate of N can be reduced by banding rather than broadcasting fertilizer N at planting, which not only enhances economic profitability for producers but also reduces the risk of adverse environmental consequences.…”

“…A limited starter 15 N rate (30 kg ha −1 ) may account for the ineffectiveness of band‐placed urea for increasing NDF 15 F at harvest in the study by Suwanarit et al. (1986).…”

“…Relative to surface broadcasting, significant yield increases have been reported for subsurface banding with either 5 × 5 (Gordon & Whitney, 1995) or midrow (Bandel et al., 1984) placement, although no such increases were reported in other cases (Bandel et al., 1984; Lehrsch et al., 2000; Shapiro et al., 2016). Further evidence supporting the effectiveness of subsurface band placement of starter fertilizer has been provided by isotopic investigations, which demonstrate higher fertilizer 15 N uptake efficiency (F 15 NUE) than for broadcasting in some field trials (Maddux et al., 1991; Suwanarit et al., 1983) but not others (Maddux et al., 1991; Suwanarit et al., 1986). In contrast, Greub et al.…”