Upland rice under no-tillage preceded by crops for soil cover and nitrogen fertilization

Edemar Moro,Carlos Alexandre Costa Crusciol,Heitor Cantarella,Adriano Stephan Nascente

doi:10.1590/s0100-06832013000600023

Abstract

The grain yield of upland rice under no-tillage has been unsatisfactory and one reason could be the nitrate/ammonium balance in the soil. Cover crops and nitrogen fertilization can be used to change the nitrate/ammonium relation in the soil and improve conditions for the development of upland rice in the no-tillage (NT) system. The aim was to study the effect of cover crops and nitrogen sources on grain yield of upland rice under no tillage. The study was carried out on the Fazenda Experimental Lageado, in Botucatu, State of São Paulo, Brazil, in an Oxisol area under no-tillage for six years. The experiment was arranged in a randomized block split-plot design with four replications. The plots consisted of six cover crop species (Brachiaria brizantha, B. decumbens, B. humidicola, B. ruziziensis, Pennisetum americanum, and Crotalaria spectabilis) and the split-plots of seven forms of N fertilizer management. Millet is the best cover crop to precede upland rice under NT. The best form of N application, as nitrate, is in split rates or total rate at topdressing or an ammonium source with or without a nitrification inhibitor, in split doses. When the cover crops C. spectabilis, B. brizantha, B. decumbens, B. humidicola, and B. ruziziensis preceded rice, they induced the highest grain yield when rice was fertilized with N as ammonium sulfate source + nitrification inhibitor in split rates or total dose at topdressing.

Highlights

Cover crops are plant species used to cover and protect the soil against erosion and nutrient loss through leaching or runoff (Dabney et al, 2001)
The plots consisted of six species of cover crops (Brachiaria brizantha, B. decumbens, B. humidicola, B. ruziziensis, Pennisetum americanum, and Crotalaria spectabilis) and split plots and seven forms of N fertilizer management, applied 0 and 30 days after emergence (DAE) of the rice seedlings [Control: no N fertilization; Calcium nitrate, NO (40+40 kg ha-1); NO (0+80 kg ha-1); Sulfate ammonium, NH (40+40 kg ha-1); NH
According to Pacheco et al (2011) and Nascente et al (2013a,b), these cover crops are well-known for producing high amount of biomass, which is very important for regions such as the Cerrado, where soil fertility is low

Summary

Introduction

Cover crops are plant species used to cover and protect the soil against erosion and nutrient loss through leaching or runoff (Dabney et al, 2001) They contribute to carbon sequestration and can improve soil quality and increase the soil organic matter, nutrient cycling and cation exchange capacity (Aranda et al, 2011). Cover crops are very important in the no-tillage (NT) system, a technique used on about 25 million hectares of agricultural production in Brazil (Febrapdp, 2012) and on around 120 million hectares worldwide (FAO, 2006) In this context, we address rice, which is a staple grain in the diet of half the world’s population, produced in both lowland and upland ecosystems (Santos et al, 2006). Since the water availability for rice irrigation by the flooding method is decreasing in Asia, mainly in China and India, due to the rapid growth of industry and urban centers (Feng et al, 2007)

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Conclusion