Inter-row crop competition for band-injected ammonium nitrate

Abstract

Inter-species competition for applied nutrients may be managed by weed control in cultivated communities. However, intra-crop competition may still occur. Thus, regarding a fertilizer band as a finite nutrient source, individual rows of a cereal crop may compete for the applied nitrogen. The aim was to explore the partition of applied N between crop rows affected by the displacement of the fertilizer band relative to the rows. In a micro-plot experiment, a 15 N-ammonium-15 N-nitrate solution was injected in four positions parallel to two rows of spring wheat (Triticum aestivum ssp. vulgare). The course of 15 N crop uptake in each row was estimated by a sigmoid growth function using eight samplings during the elongation phase. The estimated parameters were used for calculating the asymptotic value (a), the time until a/2 was reached (T 0.5a ), and the uptake rate at this time (MaxRate), and related to the distance between the crop row and fertilizer band. The a-value decreased by 5.1%-point recovery cm −1 , T 0.5a increased by 0.5 day cm −1 and the MaxRate decreased by 0.3%-point recovery day −1 cm −1 . Placement of the fertilizer band centred between two crop rows caused an even access to the applied nitrogen, but a parallel displacement from the centre by a few centimetres significantly affected the parameters. The proliferation of the roots in the soil and thus the time until the roots reached the fertilizer zone is assumed to cause the inter-row competition for the band-injected N source. The access to the fertilizer band was clearly reflected in the dry matter production causing an uneven crop stand. The consequences of inter-row crop competition for a band-injected N source with respect to grain yield and grain quality were not explored, but attention on these parameters are required, particularly in the production of high quality wheat grains.

Competition between weeds and spring wheat for 15N‐labelled nitrogen applied in pig slurry

“…The contrasting treatment effects in weed and crop make them complementary with respect to total plant 15 N recovery. A similar offset effect was recorded between two crop rows competing for band injected ammonium nitrate (Petersen, 2005). The SB–CR distance effect on the final weed and crop 15 N recovery ( a ‐value) was about twice that of sowing time postponement, with an interaction intensifying both effects.…”

“…The difference may be related to the dry period of 3 weeks from the time of crop emergence in the previous experiment compared with only 10 days without precipitation during the second and third week after emergence in this experiment. However, the crop MaxRate was about half of the 6.3%(recovery) day −1 estimated for injection of an ammonium nitrate solution in a growing spring wheat crop (Petersen, 2001) but within the range of 1–4%(recovery) day −1 reported by Petersen (2005) for crop rows competing for banded ammonium nitrate. Also the change in crop MaxRate caused by the increase in SB–CR distance (Table 5) is about half of the −0.12%(recovery) day −1 cm −1 estimated by Petersen (2001), and even only 20% of the change estimated by Petersen (2005).…”

“…Dividing the difference between the 2 and 12cm treatments by the actual distances, the decrease in crop 15 N recovery with increasing SB–CR distance corresponds to the increase in weed 15 N recovery (Table 5). The decrease in crop 15 N recovery of −1.6 to −2.2%(recovery)cm −1 was less than half of the −5.1%(recovery)cm −1 estimated by Petersen (2005) for two crop rows competing for band‐injected ammonium nitrate after crop emergence in weed‐free conditions. In contrast, also for weed‐free conditions, Petersen (2001) reported a minor and non‐linear decrease of −0.036 × (distance in cm) 2 in the final crop 15 N recovery with increasing distance between a single crop row and the band of ammonium nitrate injected after crop emergence.…”

“…Competition of slurry N 109 between two crop rows competing for band injected ammonium nitrate (Petersen, 2005). The SB-CR distance effect on the final weed and crop 15 N recovery (a-value) was about twice that of sowing time postponement, with an interaction intensifying both effects.…”

Placement of nitrogen, phosphorus and potassium fertilizers by drilling in spring barley grown for malt without use of pesticides

“…Thus, fertilizer placement has the potential to increase crop growth and reduce weed growth, although the effect on weed growth may depend on weed population and density. Furthermore, a short distance of only a few centimetres between the crop row and the fertilizer band is important as it gives the crop a competitive edge in the competition for applied N (Petersen, 2005a), although all crop rows need to have even access to the fertilizer band (Petersen, 2005b). The increase in the ratio of crop:weed growth in the stem elongation phase has two positive effects: 1) The competitiveness of the crop and 2) the ability for the crop to withstand mechanical weed control may both be increased (Rasmussen et al, 1996).…”