The Range of the Critical Nitrogen Dilution Curve for Maize (Zea mays L.) Can Be Extended Until Silage Maturity

Abstract

The third kind of indicators relies on total N concentration of specific plant organs or the whole plant, as The concept of critical N concentration (Ncrit) assumes at any time for example, in the concept of Ncrit. At any growth a minimum shoot N concentration necessary for maximum biomass production. For maize (Zea mays L.), Ncrit has of now been confirmed stage of a crop, Ncrit is defined as the minimum N only from emergence to silking plus 25 d. These results were based concentration required for maximum crop growth rate on mineral N fertilization. In the present study, we verified that the (Ulrich, 1952). It was demonstrated that the Ncrit can validity of the concept can be extended to silage maturity and that it be assumed as a mononomial function of aboveground is not only applicable to mineral but also to organic N fertilizer. Our biomass, called the critical N dilution curve. Based on investigation included a 3-yr N fertilization experiment comprising the Ncrit, a N nutrition index (NNI) can be defined as four mineral N fertilization rates (0, 50, 100, and 150 kg N ha Ϫ1 ) the ratio of actual N concentration to Ncrit (Lemaire and three slurry treatments (0, 20, and 40 m 3 ha Ϫ1 ), respectively. et al., 1989). An NNI value of 1.0 or larger indicates A quadratic-plateau model was used to determine Ncrit values. An non-N-limiting growth, whereas NNI values below 1.0 analysis of covariance indicated that the Ncrit-to-biomass relationship correspond to N deficiency situations. The concept of was extendible to the postsilking stages. The Ncrit [g N kg Ϫ1 dry matter (DM)] was then successfully described by a mononomial function of Ncrit was successfully applied to various crops, e.g., biomass W (t DM ha Ϫ1 ): Ncrit ϭ 34.12·W Ϫ0.391 . We suggest restricting grasses (Lemaire and Salette, 1984), wheat (Triticum the model to growth stages with biomass exceeding a threshold of aestivum L.) (Justes et al., 1994), rapeseed (Brassica 1 t ha Ϫ1 . Model validation against an independent data set comprising napus L.) (Colnenne et al., 1998), rice (Oryza sativa different hybrids and soil conditions indicated a satisfactory separation L.) (Sheehy et al., 1998), and grain sorghum (Sorghum of N-limiting and non-N-limiting growth. The Ncrit concept thus seems bicolor L.) (van Oosterom et al., 2001).to provide an efficient tool for assessing the N status of forage maize With respect to maize, Cerrato and Blackmer (1991) for mineral and organic N fertilizers and for a broad range of hybrids, concluded that for grain yield, the Ncrit of the leaf climates, and soil conditions. opposite or below the ear is not a sensitive indicator of the N status. Similarly, studies of Binford et al. (1992) indicated that for early growth stages, the total N con-Inst. of Crop Sci. and Plant Breeding, Dep. of Grass and Forage farmers would record their forage maize yield and that Sci./Organic Agric., Christian-Albrechts-Univ. Kiel, Olshausenstr. 40, the mononomial model extends until silage maturity,

N, P, and S fertilization effects on industrial hemp in Saskatchewan

“…Statistically significant curvilinear responses to N fertilizer rate for hemp height and yield were further explored with a non-linear segmented quadratic-plateau model (Herrmann and Taube 2004). The segmented model was fit with the PROC NLMIXED procedure of SAS (SAS Institute, Inc. 1999) as follows:…”

A Review of Methods to Improve Nitrogen Use Efficiency in Agriculture

“…The concentration of N decreases with increase in crop biomass, sometimes referred to as "dilution" [62]. The critical N dilution curve range for corn could be used up to the silage maturity [63]. The concept of critical N may be more practical in small-scale agricultural systems, but it is usually not practical for large-scale commercial agriculture.…”

“…Corn yield prediction is related to plant population, plant size, uptake of N at V6 [63]. Therefore, the yield can be estimated at V6 growth stage although some of the components of corn yield may already be established by V6 [128].…”

Improved estimation of nitrogen uptake in grasslands using the nitrogen dilution curve

“…The critical N dilution curve represents the upper limit of plant N concentration with which maximum biomass yield can be achieved during growth. Both critical and general N dilution curves have been empirically determined for many crops (Flénet et al 2006;Gislum and Boelt 2009;Herrmann and Taube 2004;Lemaire et al 2008;Marino et al 2004). Values below the critical N dilution curve represent sub-optimal nutrient conditions and values above represent supra-optimal conditions (Gastal and Lemaire 2002).…”