Suchergebnisse

Depending on how groundwater has been collected and used, the severity of the rainfall, and the following aquifer recharge, the quality of irrigation fluids differs between regions, nations, and even towns. In hot, arid regions with limited rainfall, the salinity of groundwater used for agriculture rises, limiting the variety of crops that may be produced. Therefore, determining the quality of the irrigation water is essential. How well water works for irrigation relies on how much and what kinds of soluble salts are present in the solution. In regard to the four fundamental standards of water salinity (electrical conductivity), sodium risk (sodium adsorption ratio-SAR), residual sodium carbonates (RSC), and ion toxicity, the amount and make-up of soluble salts in a solution are reviewed. We talk about the risks associated with boron and chlorides. For convenience, several plant species' boron tolerance levels are given. The updated water quality diagram created by the US Salinity Laboratory Staff in 1954 is the most significant section of this review. The salinity of most irrigation fluids is more than 2250 S cm-1, which is not represented in this picture. The water classification diagram was expanded to include salinities up to 30,000 S cm-1 in order to handle EC values larger than 2250 S cm-1. The categories for salinity and sodicity presented here can be used to select and manage crops in an educated manner. Methods for controlling water sodicity with gypsum and lowering water salinity by combining different waters are described with examples.

Corn has been the most used plant for the production of silage of high bromatological value, aiming at feeding dairy cows of medium to high productivity. Several techniques have been proposed to increase the productivity of crops and the bromatological quality of silages, including new agricultural practices in the implantation and management of crops and also new procedures during cutting and ensiling. In the present work, soil fertility, nutritional status, dry matter production, nutrient removal and chemical quality of maize destined for silage were evaluated in four high productivity crops. The evaluations were carried out in rural properties in the Zona da Mata Mineira, which intensively use the production of corn silage to feed dairy cows. Samplings for the evaluation of soil fertility, nutritional status and production and accumulation of nutrients were carried out systematically. In the female inflorescence emission phase, the leaf blade was analyzed for N, P, K, Ca, Mg, S, B, Cu, Fe, Mn and Zn contents, systematically sampling seven areas of 3, 5 m2 each. When the aerial biomass of the plants presented an average of 33% of dry matter, the forage production of the crop was evaluated, sampling again, in the same areas used to evaluate the soil fertility and the nutritional status of the plants. The corn was cut at about 20 cm above the ground and the plant material was weighed and passed through a forage chopper. Subsamples of this material were analyzed for N, P, K, Ca, Mg and S contents. Soil fertility in the crops of the small rural properties assessed was medium to high, with phosphorus contents ranging from 10 to 20 mg dm- 3, while for potassium this variation ranged from 40 to 89 mg dm-3. In the soils of the four analyzed crops, there was no exchangeable aluminum in the 0 to 20 cm layer, and in the 20 to 40 cm layer, aluminum saturation in crops 1 and 3 was also small, less than 5%. It was found that all crops had adequate mineral nutrition for both macros and micronutrients. The production of dry matter and nutrient accumulation in the aerial biomass of maize in the crops were high. The average value of dry matter accumulation was close to 20.0 t per hectare, and the average removal of nutrients, by harvesting the aerial part of the corn for silage, was 247, 34, 245, 34, 23 and 22 kg per hectare for N, P, K, Ca, Mg and sulfur, respectively. The average values of crude protein, NDF, ADF, lignin and starch were, respectively, in g kg-1, 78; 460; 258; 40 and 277, characterizing forage of good bromatological quality.

O milho têm sido a planta mais usada para a produção de silagem de alto valor bromatológico, visando a alimentação de vacas leiteiras de média a alta produtividade. Várias técnicas têm sido propostas para aumentar a produtividade das lavouras e a qualidade bromatológica das silagens, incluindo novas práticas agrícolas na implantação e condução das lavouras e também novos procedimentos durante o corte e a ensilagem. No presente trabalho avaliou-se a fertilidade do solo, ao estado nutricional, a produção de matéria seca, a remoção de nutrientes e a qualidade bromatológica do milho destinado a ensilagem, em quatro lavouras de alta produtividade. As avaliações foram realizadas em propriedade rurais da Zona da Mata Mineira, que utilizam intensamente a produção de silagem de milho para a alimentação de vacas leiteiras. As amostragens para a avaliação da fertilidade do solo, do estado nutricional e da produção e acúmulo de nutrientes foram realizadas de forma sistemática. Na fase de emissão de inflorescência feminina o limbo foliar foi analisado quanto aos teores de N, P, K, Ca, Mg, S, B, Cu, Fe, Mn e Zn, amostrando-se de forma sistemática, sete áreas de 3,5 m2 cada. Quando a biomassa aérea das plantas apresentou em média 33% de matéria seca, avaliou-se a produção de forragem da lavoura, amostrando-se novamente, nas mesmas áreas utilizadas para avaliação da fertilidade do solo e do estado nutricional das plantas. O milho foi cortado a cerca de 20 cm acima do solo e o material vegetal foi pesado e passado em picadeira de forragem. Subamostras desse material foram analisadas quanto aos teores de N, P, K, Ca, Mg e S. A fertilidade do solo nas lavouras das pequenas propriedades rurais avaliadas foi de média a alta, com teores de fósforo variando de 10 a 20 mg dm-3, enquanto para o potássio esta variação foi de 40 a 89 mg dm-3. Nos solos das quatro lavouras analisadas não havia alumínio trocável na camada de 0 a 20 cm, e na camada de 20 a 40 cm, a saturação por alumínio, nas lavouras 1 e 3 também foi pequena, menos de 5%. Constatou-se que todas as a lavouras estavam com nutrição mineral adequada tanto para os macros quanto para os micronutrientes. A produção de matéria seca e acúmulo de nutrientes na biomassa aérea do milho nas lavouras foram altas. O valor médio de acúmulos de matéria seca foi próximo a 20,0 t por hectare, e a remoção média de nutrientes, pela colheita da parte aérea do milho para a ensilagem, foi de 247, 34, 245, 34, 23 e 22 kg por hectare para o N, P, K, Ca, Mg e o enxofre, respectivamente. Os valores médios de proteína bruta, FDN, FDA, lignina e amido foram respectivamente, em g kg-1, 78; 460; 258; 40 e 277, caracterizando forragem de boa qualidade bromatológica.

Phosphorus applied when planting sugarcane ensures, in most cases, an adequate supply of the element for the cane plant and for the first regrowth, however, this supply may be inadequate for subsequent regrowths. The objective of this research was to evaluate the nutritional status, production, and forage quality of the sugarcane variety RB92579, as a function of the phosphorus fertilization applied in the fourth regrowth of the sugarcane, in soil with a sandy texture, with a P content of 15 mg dm-3, in the layer from 0 to 20 cm. The study consisted of five doses of phosphorus (30, 45, 60, and 90 kg of P ha-1.) and another control treatment, with the phosphate fertilizer applied at the bottom of the furrows opened between the rows of the fourth regrowth cane. For the quality of the broth, average values of 19.85% were obtained for soluble solids; 14.04% for apparent sucrose in the culms; 88.43% for broth purity; 13.70% for stalk fiber and 140.9 kg of recoverable sugars per ton of industrialized stalks. The average productivity of industrialized stalks and total recoverable sugars was 71.2 t per hectare and 10.1 t per hectare. Probably the lack of response to phosphorus fertilization was due to the large volume of rain in the maximum growth phase of the crop, May to August, 396 mm, which far exceeded the annual average, resulting in greater P diffusion and lower minimum concentration, lower than that existing in the soil of the study area.

Avaliou-se o estado nutricional, a qualidade do caldo e a produção de açúcar das variedades de cana-de-açúcar RB867515 e RB92579, no ciclo de cana-planta, em função de doses de magnésio aplicado no fundo do sulco de plantio. O estudo, instalado em solo com teor de Mg igual a 0,61 cmolc dm-3, foi conduzido em delineamento experimental em blocos casualizados com quatro repetições. O estudo foi um fatorial 2 x 5: duas variedades de cana-de-açúcar: RB867515 e RB92579 e, cinco doses de magnésio: zero, 60, 120, 180 e 240 kg por hectare, utilizando como fonte de Mg, o óxido de magnésio comercial. As parcelas foram constituídas de sete sulcos de cinco metros de comprimentos com 1,0 metro de espaçamento. Todas as parcelas receberam adubação fosfatada e potássica na dose de 100 kg de fósforo e 150 kg de potássio por hectare, não havendo adubação nitrogenada. Na fase de crescimento máximo da cana-de-açúcar foi avaliado o estado nutricional da cana-de-açúcar. Cerca de um ano após o plantio, quando a cana estava madura, foi colhida a cana-planta, para a avaliação da qualidade do caldo e a produção de açúcar das variedades. Não houve efeito da adubação com magnésio em nenhuma das variáveis analisadas. Em relação aos teores de nutrientes na folha +3 constatou-se deficiência nutricional apenas para o potássio, cobre e manganês. A RB92579 teve produtividade média de colmos industrializáveis e de açúcares, respectivamente de 96,0 e 13,7 toneladas por hectare, superando a RB867515 em cerca de 10%. Os resultados desse estudo confirmam relatos de outros pesquisadores que citam que teores de Mg da ordem de 0,50 cmolc dm-3 são suficientes para uma adequada nutrição da cana-de-açúcar.

The nutritional status, juice quality and sugar production of sugarcane varieties RB867515 and RB92579 were evaluated in the cane-plant cycle, as a function of magnesium doses applied at the bottom of the planting furrow. The study, installed in soil with a Mg content equal to 0.61 cmolc dm-3, was conducted in an experimental design in randomized blocks with four replications. The study was a 2 x 5 factorial: two sugarcane varieties: RB867515 and RB92579, and five doses of magnesium: zero, 60, 120, 180 and 240 kg per hectare, using magnesium oxide as a source of Mg. commercial magnesium. The plots consisted of seven furrows of five meters in length with 1.0 meter spacing. All plots received phosphorus and potassium fertilization at a dose of 100 kg of phosphorus and 150 kg of potassium per hectare, with no nitrogen fertilization. In the maximum growth phase of sugarcane, the nutritional status of sugarcane was evaluated. About a year after planting, when the cane was mature, the cane plant was harvested to assess the quality of the juice and the sugar production of the varieties. There was no effect of magnesium fertilization on any of the analyzed variables. Regarding the nutrient content in leaf +3, nutritional deficiency was found only for potassium, copper and manganese. The RB92579 had an average productivity of industrializable stalks and sugars, respectively of 96.0 and 13.7 tons per hectare, surpassing the RB867515 by about 10%. The results of this study confirm reports by other researchers who mention that Mg contents of the order of 0.50 cmolc dm-3 are sufficient for adequate nutrition of sugarcane.

For crops to have good productivity, it is necessary to adopt agricultural practices that ensure an adequate supply of water and nutrients, and neutralize toxic elements in the soil, especially exchangeable aluminum, both in the arable layer and in the subsurface. One of these agricultural practices usually employed in both small and medium and large rural properties is the correction of soil acidity, which aims, in addition to neutralizing exchangeable aluminum, to provide calcium and magnesium for plants. Several materials have been used to correct soil acidity, with carbonates, oxides, hydroxides or silicates as neutralizing components. In the present work, the reactivity of two acidity correctives was evaluated in a soil of medium texture, with high aluminum saturation: 72.96%. The correctives used were a steel slag (calcium silicate), and a dolomitic limestone, applied in doses equivalent to one, one and a half, two, and two and a half times the analytically predicted amount, to raise the base saturation to 60%, using calcium acetate with H+ + Al3+ extractor. The study also included a control treatment, which did not receive acidity correction. The method used to evaluate the reactivity of the two correctives was soil incubation. The block design was used, with six repetitions per concealer dose. The experimental units were plastic bags with 3.0 kg of soil. After mixing the correctives with the soil, in the doses corresponding to each treatment, they were transferred to plastic bags and incubated at 70% of the maximum water retention capacity for ninety days. After the incubation period, the soil was analyzed for pH in CaCl2, pH in H2O, exchangeable aluminum (Al+3), and base saturation (V %). Steel slag and dolomitic limestone had the same efficiency to neutralize aluminum and increase base saturation. The pH in CaCl2 and pH in H2O were highly correlated, with the average pH in H2O being 0.50 units greater than the pH in CaCl2. The equation to relate pH in CaCl2 to pH in H2O was Y= 1.0273 x + 0.4716, with R2 = 0.9730. Complete neutralization of Al+3 occurred when the soil pH was raised to 5.03 (pH in CaCl2) or pH 5.50 (pH in H2O). The extraction of H+ + Al3+ with calcium acetate resulted in an underestimation of the cation exchange capacity at pH 7.0 (CTC T), and consequently of the corrective dose to be applied. On average, there was a need to double the amount of concealer predicted analytically to reach the desired base saturation. The equation to relate base saturation with corrective doses, in CaCO3 equivalents, was Y= 9.1476x + 3.8439, with R2 of 0.9449.