Disponibilidade de água e produção de arroz em função de doses de concentrado zeolítico
ABSTRACT O uso de condicionadores no solo possibilita aumentar a capacidade de retenção de água e nutrientes dos solos arenosos. As zeólitas são minerais alumino-silicatos cristalinos hidratados, estruturados em redes tridimensionais rígidas e de ocorrência natural e que podem ser utilizados como condicionador natural do solo. O objetivo deste trabalho foi avaliar o efeito de doses de um concentrado do mineral zeólita sobre a retenção de água de um Neossolo Quartzarênico e a produção do arroz em duas freqüências de irrigação. Os tratamentos utilizados foram 4 níveis do concentrado zeolítico: testemunha, 33,3; 66,7 e 100,0 g kg -1 de solo. As plantas de arroz foram cultivadas com irrigação diária e com intervalos de um dia. Os resultados indicam que com o uso do concentrado zeolítico foi possível aumentar a retenção e disponibilidade de água no solo. Houve aumentos em relação à testemunha de 10, 38 e 67% na capacidade de água disponível (CAD) e de 15%; 51% e 111% na água facilmente disponível (AFD) para as doses de 33,3; 66,7 e 100,0 g kg -1 . The use of soil conditioners are an alternative to improve soil water and nutrient retention. Zeolites are hydrated crystalline aluminate-silicates structured in rigid three-dimensional nets with natural occurrence which can be used as a natural soil conditioner. The main objective of this research was evaluating the effect of levels of a mineral zeolite concentrate on the water retention and available water capacity of an Entisol (Sandyl/Quartzipsament) and the rice growth and yield in two irrigation frequencies. Treatments consisted of 4 levels of the zeolitic concentrate: control, 33.3; 66.7 and 100.0 g kg -1 . Rice was grown with daily irrigation and one day interval. Results indicated that the zeolitic concentrate increased the water retention and availability of the sandy soil. Available water capacity increased 10, 38 and 67% and easily available water increased 15, 51 and 111% in relation to the control, respectively, with
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ABSTRACT: Zeolites are hydrated crystalline aluminosilicate minerals of alkaline and alkaline earth metals, structured in rigid three dimension nets, organized by AlO 4 and SiO 4 tetrahedral and are of natural occurrence. This report describes the characterization and application of the Brazilian zeolitic sedimentary rock as a release fertilizer and soil conditioner. The characterization of the head samples showed that it is composed of the zeolite stilbite intermixed with a smectitic clay mineral, and quartz. A low-cost quartz separation technique was established. Enrichment of concentrated natural zeolite was carried out: zeolite + KNO 3 , zeolite + K 2 HPO 4 and zeolite + H 3 PO 4 + apatite and the concentrated zeolite. These materials were tested with Rangpur lime rootstock and an experiment was also carried out with successive crops grown on the same substrate: lettuce, tomato, rice, and Andropogon grass. The results indicated that N, P and K enriched zeolite was an adequate slow-release source of nutrients to plants. Other green house and field experiments with concentrated zeolite applied with urea showed reduction of losses of ammonia by volatilization and improved in N use efficiency by maize. Concentrated zeolite also increased water retention and the available water capacity of a sand soil. Introduction The use of minerals for agricultural purposes is becoming widespread (Van Straaten 2006), and zeolitic concentrates have a special niche in this category. Zeolite minerals are crystalline hydrated aluminosilicates of alkali or alkaline-earth metals, structured in three-dimensional rigid crystalline network, formed by the tetrahedral AlO 4 and SiO 4 , which come together to compose a system of canals, cavities and pores (Ming and Mumpton 1989). The worldwide number of identified natural zeolite – about forty –demonstrates both their great variety and the present-day interest on their potential applications in the industry and the agriculture (Ming and Dixon 1987). These minerals have three main properties, which are of great interest for agricultural purposes: high cation exchange capacity, high water holding capacity in the free channels, and high adsorption capacity (Mumpton 1999). Sediment occurrences of this aluminosilicate are known to exist in northern areas of Brazil (Rezende and Angelica 1999). Zeolites improves the efficiency of nutrient use by increasing the availability of P from phosphate rock, the utilization of N-NH 4 + and N-NO 3 -and reduced losses by leaching of exchangeable cations, especially K + (Barbarick et al. 1990; Allen et al. 1995; Williams and Nelson 1997; Leggo 2000; and Pickering et al. 2002). Zeolites mixed with phosphate rock, can act as controlled delivery system and renewable source of nutrients for plants (Allen et al. 1995; Barbarick et al. 1990). The increased efficiency of N utilization when urea is used together with zeolite was demonstrated by Crespo (1989), Bouzo et al. (1994), Carrion et al. (1994) and He et al. (2002) that achieved increasing of N use efficiency, N uptake and dry matter yield and reductions of losses by ammonia volatilization. Zeolites also improves the efficiency of water use by increasing the soil water holding capacity and its availability to plants (Xiubin and Zhanbin 2001; Bernardi et al. 2008). While literature shows that zeolites are useful for increasing nutrient use efficiency in a range of crops, little information exists on the use of stilbite, in agricultural systems especially on acid soils. The objective of this report was to characterize and test the application of Brazilian zeolitic sedimentary rock as a slow release fertilizer and soil conditioner.