Response of Spring Wheat to N Fertilizer Placement, Row Spacing, and Wild Oat Herbicides in a No‐Till System¹

Abstract

A 2-year study was conducted on a north facing Thatuna silt loam (fine-silty, mixed, mesic Xeric Argialbolls) to evaluate the influence of N fertilizer placement, crop row spacing, and wild oat (Avena fatua L.) herbicides on wild oat populations and wheat (Triticum aestivum L. ) yield in no-till spring wheat. The treatments were factorial arrangements of ammonium nitrate either surface applied preplant or banded 50 mm below the crop seed at planting; wild oat control using triallate (S-(2,3,3-trichloroallyl)diisopropylthiocarbamate) preemergence, difenzoquat (1,2-dimethyl-3,5-diphenyl-lH-pyrazolium) post-emergence, or no herbicide (check); and crop row spacings of either 200, 300, or 400 mm. Surface-applied fertilizer N significantly increased wild oat populations compared with banding the N fertilizer below the seed, but had no effect on dry weight or N uptake. Banded N increased total dry weight N uptake, and grain yields of wheat. These responses indicate that banded fertilizer N was positionally more available to wheat than was broadcast N, but banding N did not reduce availability of N to wild oat. However, surfaceapplied N stimulated wild oat emergence. Triallate decreased wild oat populations compared to difenzoquat or no herbicide, but was no more effective than difenzoquat in reducing wild oat dry weight and total .Kjeldahl N uptake. Both herbicides reduced wild oat dry weight as compared to the no herbicide check and significantly increased wheat yields. Row spacing did not affect wild oat dry weight or total N uptake, but the 200 m row increased wheat dry weight, total Kjeldahl N uptake, and grain yields compared to the 300 and 400 em rows. There were no significant interactions.

Weed growth and crop yield loss in wheat as influenced by row spacing and weed emergence times

“…In contrast, sowing wheat in narrowly spaced rows might have allowed the crop to efficiently exploit space, minimising the space available for weed growth. Furthermore, uniform distribution of plants in narrow row spacing might have resulted in efficient use of available resources like nutrients, light, and water (Reinertsen et al, 1984;Weiner et al, 2001;Fig. 1.…”

Soil erosion, runoff and nutrient losses in an avocado (Persea americana Mill) hillside orchard under different groundcover management systems

“…However, during decomposition of cover crop residues there may be an initial period of soil N-immobilization, followed by a period of net N re-mineralization (Kumar and Goh 1999; Recous et al 1999). The duration of this period depends on the C-to-N ratios of the crop residue (Reinertsen et al 1984), lignin and polyphenol contents (Kumar and Goh 1999), and initial soil N concentrations (Reinertsen et al 1984;Recous et al 1995), among other factors. In the present study, uptake of N by groundcovers, retention of N during initial groundcover residue decomposition, and the low initial soil organic matter content at this site, could have interacted to reduce soil N availability transiently in the GC and VS plots compared with the BS treatment (Nyborg et al 1995a).…”

Influence of source, method of placement and simulated rainfall on the recovery of 15N-labelled fertilizers under zero tillage

“…Reduced availability of applied N can result in lower yields that can negate lower labour, fuel and machinery costs associated withZT compared to CT. To improve N utilization efficiency under ZT, N fertilizer placement in bands below the soil surface can prevent N loss through ammonia volatilization (Bouwmeester et al 1985) and improve the availability of fertilizer N to plants under ZT (Mengel et aL 1982 Touchton and Hargrove 1982;Reinertsen et al 1984).…”