Apparent recovery of fertilizer n by vegetable crops

Abstract

Apparent recoveries of fertilizer N by crops were studied as their treatment in simulation models is a serious problem. Multi-level N fertilizer experiments in which fertilizer was broadcast and incorporated in soil immediately before drilling were carried out on a range of vegetable crops on adjacent sites of the same field. At final harvest, apparent recovery always declined approximately linearly with the increase in fertilizer N even when less was applied than was needed for maximum uptake; this contrasts with the well-known constancy of apparent recovery of Gramineae (winter wheat and grass) over widely different rates. At the seedling stage (of vegetables), when N-uptakes were very small, N-uptake and invariably dry weight, unexpectedly increased with the increase in fertilizer N until very high levels were reached. A single simulation model, with species differences accounted for by variations in the value of only one coefficient, defined, at least qualitatively, all the various phenomena. It is argued that substantial quantities of nitrate may always remain in soil at harvest of some vegetable crops if a sufficient amount of N-fertilizer is applied by the conventional broadcast method to obtain high yields.

Nitrogen apparent recovery can be used as the indicator of soil nitrogen supply

“…The two recovery factors are required because soil nitrogen and fertiliser nitrogen may be differently available in time and space. However, the author concluded that in most cases the two recovery factors can be considered nearly equivalent; therefore the uptake efficiency of fertiliser nitrogen (apparent nitrogen recovery) can be estimated on the basis of the nitrogen uptake of the unfertilised control as proposed by other authors (Greenwood et al, 1989;Zemenchik, Albrecht, 2002;Benincasa et al, 2011;Murphy et al, 2013).…”

“…Here the general assumption is -crops equally use the same amount of nitrogen despite the external sources (fertilisers) is available or not. Regardless of facts that more mobile forms of nutrients supplied by fertilisers could be used more efficiency if present compared with soil sources this approach of plant nutrient recovery calculation is widespread (Greenwood et al, 1989;Zemenchik, Albrecht, 2002;Brentrup, Palliere, 2010;Benincasa et al, 2011;Murphy et al, 2013).…”

“…If soil is fertilised under current crop parameters, nutrient-uptake efficiency, i.e. proportion of a nutrient added to the soil that is absorbed by a plant growing in the soil (Barber, 1995) is used, or a similar value -nutrient use efficiency (NUE) (Dobermann, 2005;Benincasa et al, 2011;Janušauskaitė, 2013), or recovery of applied fertilisers (fertiliser recovery efficiency) (Greenwood et al, 1989). These concepts are similar but calculation methods and some parameters used for that might differ.…”

Nitrogen Use Efficiency of Three Maize (Zea Mays L.) Cultivars

“…The total grain yield was calculated according to the following formula: Total grain yield (tons/ha) = grain weight(g)/m2 / 100 [6]. Nitrogen use efficiency calculated as follows: NUE = grain yield/ actual amount of nitrogen added [7]. Seeds crude protein and crude fibre contents were determined following the standard methods of the Association of Official American Analytical Chemists [8].…”

Aspects of nitrogen use efficiency of cauliflower II. Productivity and nitrogen partitioning as influenced by N supply

“…The plateau level clearly is the consequence of the saturated sink capacity of the cauliflower crop. Greenwood et al (1989) compared the N response of vegetable and gramineous crops and found a linear response-plateau response more typical for gramineous than for vegetable crops where quadratic response function gave a better fit to the data. He interpreted this as the consequence of a restricted N availability especially during early growth stages of vegetable crops, where rooting density is much lower than for gramineous crops.…”