Attributes of irrigated rice as affected by soil sodicity and potassic fertilizer application

Felipe De Campos Carmona,Marquel Jonas Holzschuh,Amanda Posselt Martins,Ibanor Anghinoni

doi:10.1590/s0100-06832011000300023

Abstract

Soils of the coastal plains of Rio Grande do Sul, Brazil, are affected by salinization, which can hamper the establishment and development of crops in general, including rice. The application of high doses of KCl may aggravate the crop damage, due to the high saline content of this fertilizer. This study aimed to evaluate the effect of K fertilizer management on some properties of rice plant, grown in soils with different sodicity levels, and determine which attribute is best related to yield. The field study was conducted in four Albaqualfs with exchangeable Na percentages of 5.6, 9.0, 21 and 32 %. The management of KCl fertilizer consisted of the application of 90 kg ha-1 K2O broadcast, 90 kg ha-1 K2O in the row and 45 kg ha-1 K2O in the row + 45 kg ha-1 K2O at panicle initiation (PI). Plant density, dry matter evolution, height, SPAD (Soil Plant Analysis Development value indicating relative chlorophyll contents) index, tiller mass, 1,000-grain weight, panicle length and grain yield were evaluated. The plant density was damaged by application of K fertilizer in the row, especially at full dose (90 kg ha-1), at three sodicity levels, resulting in loss in biomass accumulation in later stages, affecting the crop yield, even at the lowest level of soil sodicity (5.6 %). All properties were correlated with yield; the highest positive correlation was found with plant density and shoot dry matter at full flowering, and a negative correlation with panicle length.

Highlights

Coastal plains of Rio Grande do Sul, Brazil, have vast areas suitable for the cultivation of irrigated rice (Oryza sativa L.), mainly because of the large availability of water resources and favorable terrain
According to Pearson & Bernstein (1959), salinity is critical to rice in the seedling and flowering stage, resulting, respectively, in plant density reduction (Oster et al, 1984; Shannon et al, 1998) and spikelet sterility (Ehler, 1960; Fraga et al, 2010), a property highly correlated to grain yield (Grattan et al, 2002)
The plant density on soil with ESP of 32 % was very low, which should be mainly attributed to the high salinity and sodicity (Table 1)

Summary

Introduction

Coastal plains of Rio Grande do Sul, Brazil, have vast areas suitable for the cultivation of irrigated rice (Oryza sativa L.), mainly because of the large availability of water resources and favorable terrain. Sodicity, both of soil and water, may be a limiting factor for cultivation in this region of the State, where the main source of irrigation is a lagoon called Laguna dos Patos. The adjacent lands under rice are subject to the deposition of Na salts in greater proportions, which could affect the establishment and development of crops in subsequent plantings. According to Pearson & Bernstein (1959), salinity is critical to rice in the seedling and flowering stage, resulting, respectively, in plant density reduction (Oster et al, 1984; Shannon et al, 1998) and spikelet sterility (Ehler, 1960; Fraga et al, 2010), a property highly correlated to grain yield (Grattan et al, 2002)

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Conclusion