The Recovery of Fertilizer Nitrogen From Various Depths Below Swards

Abstract

A microplot technique for the placement of nitrogen at depth under an established grass sward is described. The effect of nitrogen placement at various depths on the dry matter yields, root yields and nitrogen uptake of two grass sp)ecies is recorded. The results for cocksfoot and red fescue indicate that there is little fall-off in uptake of nitrogen from placement at depths down to 12 inches, and that cocksfoot also recovers substantial amounts of nitrogen from 18 inches and 2 feet. Recovery by red fescue at these depths was not investigated.Althotigh there is little difference between the two grasses in their relative ability to absorb nitrogen at the various depths, there is an indication that, weight for weight, cocksfoot roots are probably more efficient absorbers of nitrogen than those of red fescue.The significance of the findings is discussed in the light of present-day methods of fertilizer application.

Influence of the Spatial Distribution of Nitrate on the Uptake of N by Plants: A Review and a Model for Rooting Depth

“…Uptake per unit weight of roots in the subsoil was found to be up to 300 times that in the surface region. Similar results were obtained by Kernick (1960) for the recovery of fertilizer N by the shallower-rooted cocksfoot and red fescue grasses over a somewhat narrower range of placement depths, and by Hodgson (1970) for established ryegrass swards. Garwood and Williams (1967), and Herron et al (1968) showed that N recoveries from subsoil applications within the root zone could even exceed those from equivalent surface dressings when the top soil was dry.…”

“…The ability of small fractions of the root system to absorb the total plant N requirements from different depths in the soil profile has also been demonstrated in placement experiments with winter wheat (Daigger and Sander, 1976), with maize (Herron et al, 1968;Gass et al, 1971) and with established grass swards (Kernick, 1960;Garwood and Williams, 1967;Hodgson, 1970;Ogus and Fox, 1970). The results of Daigger and Sander (1976) are summarised in Fig.…”

“…Thus, in practice there is often considerable latitude in the way in which root systems may be distributed between nitrate-containing and nitrate-free regions before uptake is affected. The compensatory effect of these processes is reflected in the results of Kernick (1960), Herron et al (1968), Ogus and Fox (1970), Gass et al (1971) and Daigger and Sander (1 976) who showed that nitrate recoveries remained approximately constant (except occasionally from surface applications) over a wide range of placement depths within the rooting zone.…”

Growth, Water use and nutrient uptake from the subsoil by grass swards

“…Application of nutrients, particularly nitrogen, to the moist subsoil from which the sward was currently obtaining water substantially increased growth (Tables 4 and 6). Kernick (1960) found that uptake of nitrogen by grasses from various depths down to 12 in. was not significantly different, and that substantial amounts of nitrogen could be recovered after placement at depths down to 24 in.…”

Residual Effects of Fertilizer Nitrogen in Soil

“…Results of Kernick (1960) showed that the NO,-N below the plow layer was less effective in increasing N uptake by grass than that in the surface layer. Similar results are reported by White & Pesek (1959).…”