Elsevier

Field Crops Research

Volume 95, Issue 1, 8 January 2006, Pages 13-29
Field Crops Research

The N:P stoichiometry of cereal, grain legume and oilseed crops

https://doi.org/10.1016/j.fcr.2005.01.020Get rights and content

Abstract

A data base including grain yield, nitrogen uptake (Nu) and phosphorus uptake (Pu) was compiled to investigate the N:P stoichiometry of cereal (n = 759), grain legume (n = 413) and oilseed species (n = 421). Actual ratios and slopes of functions relating nitrogen uptake and phosphorus uptake were used to characterise N:P stoichiometry. The focus is on variability in N:P ratios of field crops, and N:P stoichiometry of crops achieving maximum yield.

N:P ratios varied between ∼20, the maximum for legumes and oilseed crops, and ∼1.5, the minimum for cereals. By definition, N:P ratios are a direct function of N uptake and an inverse function of P uptake. The expected association between N:P ratio and N uptake was not evident except for grain legumes whereas the expected relationship between N:P and P uptake was verified for all three crop types. This highlights the role of P uptake as the main source of variability in N:P stoichiometry.

The relationship between N uptake (Nu) and P uptake (Pu) for crops achieving maximum yield in each experiment was markedly non-linear. Functions of the form Nu = NmaxPu/(Pu# + Pu) described the way in which N:P stoichiometry scaled with grain yield. Maximum uptake of nitrogen (Nmax) was similar for all three crop types (≈240 kg N ha−1), but it was achieved via different avenues, i.e. high yield and low grain protein concentration for cereals compared to lower yield and higher grain protein concentration in oilseed and legume crops. Phosphorus uptake at half Nmax (Pu#) ranged from 27 kg P ha−1 for oilseeds to 14 kg P ha−1 for legumes. The N:P ratio at Pu# was 4.5 for oilseed crops, 5.6 for cereals and 8.7 for legumes. For cereals and oilseeds, over 40% of crops attaining maximum yield had N:P ratios in a relatively narrow range between 4 and 6. Variation in grain protein concentration was a major source of instability in N:P ratios of legumes.

Being at the base of agro-ecological food webs, the N:P stoichiometry of crops has implications for both decomposers and consumers, and stoichiometric concepts might be of interest in fertiliser management and modelling. Variability in N:P stoichiometry related to plant storage products, however, restricts its application.

Introduction

Crop yield is frequently constrained by availability of major nutrients, including nitrogen and phosphorus. While approaches for the diagnosis and management of crop nutrition often target individual nutrients, there is an increasing interest in integrated nutrient management. Heady et al. (1955) developed early empirical models of crop and pasture responses to multiple nutrients (NPK). Angus et al. (1993), Hedge (1996), Witt et al. (1999), Prasad et al. (2002), de Varennes et al. (2002), Kho (2000) and Duivenbooden et al. (1996) are examples of more recent theoretical and experimental attempts to understand and manage crop responses to multiple nutrients.

N:P stoichiometry and co-limitation are two important ecological concepts which can contribute to understand N–P relationships in crops. N:P stoichiometry has been interpreted in the light of evolutionary constraints on the chemical composition of living organisms (Elser et al., 1996, Sterner and Elser, 2002, Ågren, 2004). Scaling up from biomolecules to ecosystems, N:P ratios have provided a valuable link between cellular, ecosystem and evolutionary processes. Furthermore, N:P ratios have been proposed as a diagnostic tool for nutrient limitations in natural vegetation (Koerselman and Meuleman, 1996, Verhoeven et al., 1996, Güsewell and Koerselman, 2002, Güsewell et al., 2003). Co-limitation is operationally identified when the response of the system to two or more factors is greater than its response to each factor in isolation, and has been recognised at levels of organisation from cells to ecosystems (Venterink et al., 2001, Flynn, 2002). Based on economic marginal analysis, Bloom et al. (1985) proposed that a high degree of resource co-limitation is a condition for maximum growth of stressed plants. Consistently with this theory, the optimum N:P for a species has been defined as the N:P ratio where its growth is equally limited by N and P (Sterner and Elser, 2002). Rastetter and Shaver (1992) modelled plant growth under multiple-element limitation upon the assumption of an optimal ratio of mineral elements in vegetation biomass.

Agronomic studies of crop N:P stoichiometry and co-limitation are scarce. Janssen (1998) proposed that nutrient uptake efficiency, i.e. the ratio of actual uptake to potential supply, and utilisation efficiency, i.e. the ratio of yield to actual uptake, require “N, P and K perfectly in balance to reach their maximum values”. For cereals, Duivenbooden et al. (1996) calculated an optimum N:P  7. In comprehensive experiments with rice, Witt et al. (1999) estimated balanced nutrient uptakes of 14.7 kg N and 2.6 kg P per tonne of grain; this corresponds with a ratio of 5.6. Mkamilo (2004) used N:P ratios in plant tissue to assess relative nutrient limitation in maize–sesame intercrops. Recent studies of crop responses to water and nitrogen availability support the concept of high degree of co-limitation as a condition for maximising growth of stressed wheat (Sadras, 2004, Sadras et al., 2004).

This paper investigates the N:P stoichiometry of cereal, grain legume and oilseed crops. The focus is on variability in N:P ratios of field crops, and N:P ratios of crops achieving maximum yield. Ågren (2004) defined “critical ratio” as the ratio where N and P are simultaneously limiting growth. According to the theory of co-limitation (Bloom et al., 1985, Sadras, 2004) this critical ratio should correspond with maximum yield. But the large capacity of plants for excess uptake of nutrients may affect the way in which N:P stoichiometry scales with growth and yield (Sterner and Elser, 2002, Ågren, 2004). Typical N:P ratios, nonetheless, are expected to reflect the dominant chemical compounds stored in grains, e.g. protein in grain legumes versus starch in cereals.

Section snippets

Method

CAB abstracts (1973–2004) were searched using combinations of key words including nitrogen, phosphorus, uptake, and yield. The retrieved abstracts were inspected, and papers reporting grain yield and crop uptake (i.e. shoot content) of N and P were used to build the data base summarised in Table 1. Only papers from field experiments were considered.

Grain yield and nutrient uptake

Although the relationships between grain yield and nutrient uptake are well established, this section outlines the specific relationships for the data set in Table 1 to provide an agronomic background for the N:P stoichiometry in Section 3.2.

Crops summarised in Table 1 grew under contrasting soil, weather and management conditions. This caused a large variation in crop yield and uptake of nutrients (Table 2). Nutrient availability, as affected by soils and fertiliser rate, was a major source of

Concluding remarks

This study characterised the variability of N:P ratios in grain crops, and showed consistent differences among crop types. Non-linear functions relating N uptake and P uptake for crops achieving maximum yield described the way in which N:P stoichiometry scales with grain yield. Variation in protein concentration was a major source of instability in N:P ratios, particularly in grain legumes. Grain phytate concentration is a potentially important source of N:P variation that deserves further

Acknowledgements

I thank Luis Aguirrezábal, Daniel Cogliatti and Steve Milroy for valuable comments on the manuscript, Mikaela Lawrence and her colleagues at CSIRO Library for their kind assistance with the literature search, and the Grains Research and Development Corporation of Australia for financial support.

References (153)

  • X.J. Liu et al.

    Effects of non-flooded mulching cultivation on crop yield, nutrient uptake and nutrient balance in rice–wheat cropping systems

    Field Crops Res.

    (2003)
  • F.O. Olasantan et al.

    Effects of intercropping and fertilizer application on weed control and performance of cassava and maize

    Field Crops Res.

    (1994)
  • P.V.V. Prasad et al.

    Maximizing yields in rice–groundnut cropping sequence through integrated nutrient management

    Field Crops Res.

    (2002)
  • R. Aerts et al.

    The mineral nutrition of wild plants revisited: a re-evaluation of processes and patterns

    Adv. Ecol. Res.

    (2000)
  • G.I. Ågren

    The C:N:P stoichiometry of autotrophs – theory and observations

    Ecol. Lett.

    (2004)
  • L.A.N. Aguirrezábal et al.

    Calidad de productos agrícolas. Bases ecofisiológicas, genéticas y de manejo agronómico

    (1998)
  • I.P.S. Ahlawat et al.

    Dry-matter accumulation and nutrient uptake in pigeon pea (Cajanus cajan L. Huth) in relation to plant density and phosphorus fertilization

    Zeitschrift fur Acker- und Pflanzenbau

    (1983)
  • C.S. Andrew et al.

    The phosphorus nutrition of tropical forage legumes

  • J.F. Angus et al.

    Modelling nutrient responses in the field

    Plant Soil

    (1993)
  • Anon.

    Statview Reference

    (1999)
  • Anon.

    SigmaPlot 2000 User's Guide

    (2000)
  • K. Ashok et al.

    Response to phosphorus applied in rainy-season crop and nitrogen applied to wheat (Triticum aestivum) under sorghum (Sorghum bicolor)/cowpea (Vigna unguiculata)–wheat cropping system

    Ind. J. Agron.

    (2002)
  • M.S. Aulakh et al.

    Nitrogen and phosphorus requirement and ability to scavenge soil N by hybrid sunflower

    Crop Improvement

    (1996)
  • S.B. Badole et al.

    Residual effect of integrated nutrient management system of cotton on yield and nutrient uptake of summer groundnut

    J. Soils Crops

    (2003)
  • G.S. Bahl et al.

    Effect of fertilizer nitrogen and phosphorus on the grain yield, nutrient uptake and oil quality of sunflower

    J. Ind. Soc. Soil Sci.

    (1997)
  • M.R. Bajpai et al.

    A note on the irrigation and fertility levels on the yield and nutrient uptake of dwarf barley cultivar RDB-1

    Ann. Arid Zone

    (1977)
  • B. Basavaraj et al.

    Nutrient content and upake by sesame varieties as influenced by fertilizer and population levels under summer irrigated conditions

    Karnataka J. Agric. Sci.

    (2000)
  • G.D. Batten et al.

    Effect of time of sowing on grain yield, and nutrient uptake of wheats with contrasting phenology

    Aust. J. Exp. Agric.

    (1987)
  • F. Berendse et al.

    Acquisition, use and loss of nutrients

  • M.A. Bhat et al.

    Nutrient uptake and economics as affected by different sowing dates and phosphorous levels in field pea (Pisum sativum L.) under temperate conditions of Kashmir

    Adv. Plant Sci.

    (2002)
  • A.J. Bloom et al.

    Resource limitation in plants – an economic analogy

    Ann. Rev. Ecol. Syst.

    (1985)
  • K. Brahmachari et al.

    Potassium and sulphur nutrition of crops with or without organic manure under jute (Corchorus olitorius)–rice (Oryza sativa)–rapeseed (Brassica campestris) sequence

    Ind. J. Agron.

    (2000)
  • B.S. Brar et al.

    Integrated use of farmyard manure and inorganic fertilizers in maize (Zea mays)

    Ind. J. Agric. Sci.

    (2001)
  • A. Chakraborty et al.

    Response of brown sarson (Brassica campestris subsp. oleifera var. brown sarson) and Indian mustard (B. juncea) varieties to sulphur under red and lateritic soils of West Bengal

    Ind. J. Agron.

    (1994)
  • S.D. Chaphale et al.

    Effect of weed management on nutrient uptake of soybean and soil properties

    J. Soils Crops

    (2003)
  • W. Cheng et al.

    Nutrient accumulation and utilization in rice under film-mulched and flooded cultivation

    J. Plant Nutr.

    (2003)
  • M.K. Chowdhury et al.

    Comparison of nitrogen, phosphorus and potassium utilization efficiency in maize/mungbean intercropping

    J. Agric. Sci.

    (1994)
  • L. Cooperband et al.

    Effect of poultry litter and composts on soil nitrogen and phosphorus availability and corn production

    Nutr. Cycl. Agroecosyst.

    (2002)
  • A. Dixit et al.

    Nutrient concentration and its depletion in Indian mustard (Brassica juncea) as influenced by fertilizer, irrigation and weed control

    Ind. J. Agron.

    (1996)
  • J.H. Dongale

    Yield, composition and nutrient uptake by mustard in relation to irrigation and N–P fertilization

    J. Ind. Soc. Coastal Agric. Res.

    (1990)
  • J.W. Dudley

    Seventy Generations of Selection for Oil and Protein in Maize

    (1974)
  • N.V. Duivenbooden et al.

    Nitrogen, phosphorus and potassium relations in five major cereals reviewed in respect to fertilizer recommendations using simulation modelling

    Fert. Res.

    (1996)
  • V.P. Duraisami et al.

    Residual effect of inorganic nitrogen, composted coirpith and biofertilizer on yield and uptake of soybean in an Inceptisol

    Madras Agric. J.

    (2001)
  • J.J. Elser et al.

    Organism size, life history, and N:P stoichiometry

    BioScience

    (1996)
  • J.J. Elser et al.

    Nutritional constraints in terrestrial and freshwater food webs

    Nature (London)

    (2000)
  • M.X. Fan et al.

    Corn yield and phosphorus uptake with banded urea and phosphate mixtures

    Soil. Sci. Am. J.

    (1994)
  • D. Finney

    Was this in your statistics textbook? VI. Regression and covariance

    Exp. Agric.

    (1989)
  • K.J. Flynn

    How critical is the critical N:P ratio?

    J. Phycol.

    (2002)
  • A. Fujiwara

    The specific roles of nitrogen, phosphorus, and potasium in the metabolism of the rice plant

  • R. Gallani et al.

    Chemical composition, nutrient uptake and yield of different genotypes of chickpea on vertisols

    Crop Res. (Hisar)

    (2003)
  • Cited by (0)

    View full text