Renato Ferreira de Souza

Calagem e adubação orgânica: influência na adsorção de fósforo em solos

Liming and organic fertilizers can reduce P adsorption/precipitation in the soil, increasing the availability for plant uptake. To evaluate the effect of liming and cattle manure on phosphorus adsorption in the soil, four experiments were conducted in an entirely randomized design, in a 4 x 5 factorial layout with four replications, in a greenhouse. The treatments consisted of four liming levels (0; 0,5; 1 and 2 times the recommended dose to reach V = 60%) and five doses of cattle manure (0; 2,5; 5,0; 7,5 and 10% of the total soil volume), applied in samples of four dm3 of orthic Quartzarenic Neosol sand texture, dystrophic Red-Yellow Latosol sandy clay texture, dystrophic Red-Yellow Latosol sandy clay loam texture and dystrophic Red Latosol clay texture soils; each soil represented an experiment. The values of equilibrium phosphorus (P-rem), maximum P adsorption capacity (MPAC) and the soil P buffering index (PBI) were evaluated and subjected to fitting of multiple regression models as a function of the applied lime and cattle (bovine) manure. Liming and manure fertilizer caused a reduction of MPAC and increase in P-rem and PBI. The alterations of these values was associated to soil mineralogy and texture; P adsorption increased with the oxidic character of the soils. Results evidenced the importance of soil management systems that contemplate acidity correction and increase in organic matter levels to optimize the P use by crops.

Carbonate-silicate ratio for soil correction and influence on nutrition, biomass production and quality of palisade grass

Silicates can be used as soil correctives, with the advantage of being a source of silicon, a beneficial element to the grasses. However, high concentrations of silicon in the plant would affect the digestibility of the forage. To evaluate the influence of the substitution of the calcium carbonate by calcium silicate on the nutrition, biomass production and the feed quality of the palisade grass [Urochloa brizantha (C. Hochstetter ex A. Rich.) R. Webster], three greenhouse experiments were conducted in completely randomized designs with four replications. Experimental units (pots) contained a clayey dystrophic Rhodic Haplustox, a sandy clay loam dystrophic Typic Haplustox and a sandy loam dystrophic Typic Haplustox. Each soil received substitution proportions (0, 25, 50, 75 and 100 %) of the carbonate by calcium silicate. The increase in the proportion of calcium silicate elevated the concentrations and accumulations of Si, Ca, Mg, and B, reduced Zn and did not alter P in the shoot of plants. The effects of the treatments on the other nutrients were influenced by the soil type. Inclusion of calcium silicate also increased the relative nutritional value and the digestibility and ingestion of the forage, while the concentration and accumulation of crude protein and the neutral detergent and acid detergent fibers decreased. Biomass production and feed quality of the palisade grass were generally higher with the 50 % calcium silicate treatment.

Nutrição fosfatada e rendimento do feijoeiro sob influência da calagem e adubação orgânica

Being an essential nutrient in several cellular functions, the phosphorus frequently limits the development of the bean plant due its high capacity of adsorption to mineralogical components of the soil and low availability for the plants absorption. Soil management practices, such as the increase in the level of organic matter and liming are quite effective in the reduction of the phenomenon of adsorption of P in the soil and increase of its availability for plant absorption. Aiming to evaluate the effect of doses of bovine manure and lime on the phosphate nutrition and production of the bean plant, four experiments were conducted in the greenhouse of the Soil Science Department of the Federal University of Lavras. The experimental design was completely randomized, in a 5x4 factorial scheme with four replications, in pots containing 3 dm3 of soil samples from an Orthic Quartzarenic Neosol (RQo), a Dystrophic Red-Yellow Latosol, medium texture (LVAd-1), a Dystrophic Red-Yellow Latosol, clayey texture (LVAD-2), and a Dystrophic Red Latosol, very clayey texture (LVd), in which three bean plants were cultivated. The treatments were constituted by the application of five doses of bovine manure (0; 2.5; 5.0; 7.5, and 10 % of the volume of the soil) and four liming levels (0; 0.5; 1, and 2 times the recommended dose to reach V=60%). It were evaluated the production of dry matter of aerial part and grains and the P accumulation in dry matter of total aerial parts of beans plants. The liming and organic fertilization promoted increases in the absorption and accumulation of P, and production of grains of the bean plant, which presented the best responses with the dose of 10 % of bovine manure combined with the level 1 of liming.

Efeito do tipo de substrato e da presença de adubação suplementar sobre o crescimento vegetativo, nutrição mineral, custo de produção e intensidade de cercosporiose em mudas de cafeeiro formadas em tubetes

A utilizacao de tubetes para produzir mudas de cafeeiro (Coffea arabica L.) tornou-se uma realidade. Objetivando avaliar o uso de substratos adubados ou nao com fertilizante de liberacao gradual e seus efeitos na nutricao, na formacao, na cercosporiose e nos custos de producao de mudas de cafeeiro em tubetes, conduziu-se um experimento em viveiro, em esquema fatorial (4x2) com quatro substratos combinados com duas adubacoes, tendo quatro repeticoes. As parcelas foram constituidas por 16 tubetes de 120 mL, considerando-se como plantas uteis as seis centrais. Os tratamentos consistiram dos substratos S1= Substrato comercial I, S2 = Substrato comercial II, S3 = Substrato de eucalipto e S4 = 80% esterco de curral + 20% terra de subsolo, todos com e sem adubacao com fertilizante de liberacao gradual. No geral, os melhores substratos para formacao de mudas de cafeeiro em tubetes foram os substratos nao comerciais ou orgânicos, independentemente de receberem ou nao adubacao suplementar. Observou-se reducao da cercosporiose com a nutricao mineral, principalmente com o calcio. Com a utilizacao de todos os substratos houve ganho economico em relacao ao custo por milheiro de mudas. A maior economia foi obtida com o substrato S4, seguida do substrato S3, com melhor relacao custo/beneficio.

Atributos químicos de solos influenciados pela substituição do carbonato por silicato de cálcio

The application of silicates to soils can result in increased soil cation exchange capacity (CEC), displace anions, especially H2PO4- (diacid phosphate), neutralize the pH and Al toxicity and, in general, increase the nutrient availability to plants. However, calcium silicates may be less efficient than calcium carbonates. To evaluate the effect of calcium carbonate substitution by calcium silicate on the soil chemical properties, especially on phosphorus availability, four experiments were conducted in an entirely randomized design with four replications, in a greenhouse. The treatments consisted of five levels (0, 25, 50, 75, and 100 %) of calcium carbonate substitution by calcium silicate, with a 4:1 Ca:Mg stoichiometric and the same amount of CaO, enough to reach a 60 % base saturation. The treatments were applied to 4 dm3 samples of a sandy orthic Quartzarenic Neosol (Quartzpsament), a sandy loam dystrophic Red-Yellow Latosol (Oxisol), sandy clay loam dystrophic Red-Yellow Latosol (Oxisol) and a clayey dystrophic Red Latosol (Oxisol); each soil represented one experiment. The pH values in H2O, P, phosphorus in the equilibrium solution (P-rem), K, Ca, Mg, Si, Al, H + Al, organic matter (OM), Cu, Mn, Zn and B, sum of bases (S), effective (t) ant total (T) CEC, base saturation (V) and Al saturation (m) were submitted to analysis of variance and simple regression models fitted as a function of CaCO3 substitution by CaSiO3 levels. It was observed that carbonate substitution by silicate promoted significant increases in the values of Si, Al, H + Al and m and reduction in the values of P-rem, pH, S, t and V. The values of Mehlich 1 P, K, Mg, OM, T, Mn, Cu, and B were not influenced significantly. A reduction in Zn availability was verified in the dystrophic orthic Quartzarenic Neosol only. Calcium silicate was less efficient than calcium carbonate in the improvement of soil chemical conditions.