English

Sinencio Contreras Espinal Freddy,Cabral Da Silva Edson,Ide Franzini Vin Iacute Cius,Sakadevan Karuppan,C Eacute Sar Ocheuze Trivelin Paulo,Muraoka Takashi,Batista Teixeira Marconi

doi:10.5897/ajar2015.10684

Abstract

The use of green manures (GMs) in combination with nitrogen (N) fertilizer application is a promising practice to improve N fertilizer management in agricultural production systems. The main objective of this study was to evaluate the N use efficiency (NUE) of rice plant, derived from GMs including sunn hemp (Crotalaria juncea L.), millet (Pennisetum glaucum L.) and urea in the greenhouse. The experimental treatments included two GMs (sunn hemp-15N and millet-15N), absence of N organic source (without GM residues in soil) and four N rates, as urea-15N (0, 28.6, 57.2 and 85.8 mg N kg-1). The results showed that both rice grain and straw biomass yields under sunn hemp were greater than that of millet or without the application of GM. The NUE of rice under sunn hemp was greater than that under millet (18.9 and 7.8% under sunn hemp and millet, respectively). The urea N application rates did not affect the fertilizer NUE by rice (53.7%) with or without GMs. The NUE of GMs by rice plants ranged from 14.1% and 16.8% for root and shoot, respectively. The study showed that green manures can play an important role in enhancing soil fertility and N supply to subsequent crops. Key words: Oryza sativa L., sunn hemp, millet, isotopic diluition, nitrogen mineralization.

Highlights

Rice is a staple food for more than 50% of the world population (Fageria et al, 2010)
The objectives of this work were to evaluate (i) N use efficiency (NUE) by the rice plant derived from green manures (GMs) sunn hemp (Crotalaria juncea L.), millet (Pennisetum glaucum L.) and urea; (ii) the effect of N sources on rice yield; (iii) the contribution of N derived from the roots and above ground parts of GMs to rice; (iv) and to quantify the N in rice as affected by urea application time
Upland rice grain yield and straw biomass. Both upland rice grain yield and straw biomass were significantly influenced by N-urea application rate and GM application

Summary

Introduction

Rice is a staple food for more than 50% of the world population (Fageria et al, 2010). Nitrogen (N) is the main nutrient that affects the rice yield, because it increases the percentage of filled spikelets, increases the leaf. Brazil is the world's largest producer of upland rice, but upland rice yield is much lower than lowland-flooded rice (Fageria et al, 2010, 2011; Conab, 2015). Nitrogen is one of the most important nutrients in determining upland rice yield in Brazil, since low level of N fertilizers is used by farmers due to high cost of these fertilizers (Fageria, 2007; Fageria et al, 2010)

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Conclusion