Milson Evaldo Serafim

Disponibilidade hídrica e distinção de ambientes para cultivo de cafeeiros

This study was conducted in the districts of Sao Roque de Minas and Vargem Bonita, MG, with the aim to distinguish landscapes for coffee growing, with higher water available to the crop. Soil moisture was monitored in eight plots of coffee, and in five of them being also determined water availability for plants and soil bulk density. The plots are located in areas of Latosols and Cambisols. In one plot of each soil class, the distribution of the root system of coffee in the soil profile was studied. Soil moisture was monitored from April 2008 to February 2009, in the interval of 30 to 40 days. The soil depths of 0.2, 0.4, 0.8, 1.2 and 1.6 m were sampled, in line and between the lines of the coffee. The combination of the five plots, two sampling positions (line and between the lines) and five depths, formed the 50 Treatments used in the multivariate analysis. It was observed that soil moisture is lower in the line of coffee compared to between lines. The class of soil and plant age influence soil moisture and water availability to plants. The root system of coffee reached the depth of 1.5 to 1.7 m, in both studied soil classes. The 50 Treatments were grouped into 4, by means of the principal component analysis, according to the soil class and management.

DOSES DE GESSO EM CAFEEIRO: INFLUÊNCIA NOS TEORES DE CÁLCIO, MAGNÉSIO, POTÁSSIO E pH NA SOLUÇÃO DE UM LATOSSOLO VERMELHO DISTRÓFICO

Unbalanced amounts of Ca2+, Mg2+ and K+ in soils as a consequence of high gypsum applications can be due to the relationship in size (ionic radius) and charge density (charge/ionic radius) of each ionic species. The higher the ionic strength, the stronger is the bonding of these cations with the opposite charge ions such as OH-, SO4-2. Thus, excessive gypsum applications, disregarding the charge balance of the soil colloidal system, the ionic balance of the solution, and the CEC, can result in significant leaching of these nutrients throughout the soil profile. The aim of this study was to evaluate the effect of high gypsum rates (0, 7, and 56 t ha-1) on the pH and Ca2+, Mg2+, and K+ contents in aqueous soil extracts of a dystrophic Red Latosol with coffee. The soil was sampled in the coffee rows in the following depths: 0.15-0.25; 0.35-0.45; 0.75-0.85; 1.15-1.25, and 2.35-2.45 m, 16 months after gypsum application. The experiment consisted of four treatments: G-0 - 2 t ha-1 of gypsum was applied in total area during soil preparation, with brachiaria between coffee rows; G-7 - same as in G-0 plus 7.0 t ha-1 of gypsum applied to the coffee rows; G-56 - same as in G-0 plus 56 t ha-1 of gypsum applied to the coffee rows; and CV-7 - same as in G-7 but without brachiaria between the coffee rows. The experiments were conducted in triplicate, in a randomized block design. After 16 months, there was a reduction of the pH of the soil solution in the layers 0.15-0.25, 0.35-0.45, and 0.75-0.85 m. Gypsum improved the root environment in deeper layers, increasing Mg2+ and Ca2+ concentrations in the soil solution, but reduced K+ below 0.85 m. The amounts of exchangeable Ca2+ and Mg2+ found in the soil solution were above the critical level while exchangeable K+ was within the range indicated for the crop.

Bimodal pore distribution on soils under conservation management system for coffee crop

This study aims at detailing bimodal pore distribution by means of water retention curve in an oxidic-gibbsitic Latosol and in a kaolinitic cambisol Latossol under conservation management system of coffee crop. Samples were collected at depths of 20; 40; 80; 120 and 160 cm on coffee trees rows and between rows under oxidic-gibbsitic Latosol (LVd) and kaolinitic cambisol Latossol (LVAd). Water retention curve was determined at matrix potentials (Ψm) -1; -2; -4; -6; -10 kPa obtained from the suction unit; the Ψm of -33; -100; -500; -1,500 kPa were obtained by the Richards extractor, and WP4-T psychrometer was used to determine Ψm -1,500 to -300,000 kPa. The water retention data were adjusted to the double van Genuchten model by nonlinear model procedures of the R 2.12.1 software. Was estimated the model parameter and inflection point slope. The system promoted changes in soil structure and water retention for the conditions evaluated, and both showed bimodal pores distribution, which were stronger in LVd. There was a strong influence of mineralogy gibbsitic in the water retention more negative than Ψm -1500 kPa, reflected in the values of the residual water content.

Umidade do solo e doses de potássio na cultura da soja

The tropical soils, usually poor in potassium (K), demand potassium fertilization when cultivated with soybean (Glycine max L.) to obtain satisfactory yields. The aim of this study was to evaluate the effects of K doses and soil humidity levels on soybean agronomic characteristics. The experiment was carried out in a greenhouse, in pots with two plants, containing 5 dm3 of soil. The experimental design was completely randomized block with treatments in a 5 x 3 factorial arrangement. The K doses were 0; 30; 60, 120 and 180 mg dm-3, and the soil humidity ranged from 35 to 40; 47.5 to 52.5; and 60 to 65% of the total porosity. The characteristics appraised were: grain yield, weight of a hundred grains, total number of grains per pot, K level in the grain, number of viable pods. There was soybean response to the potassium fertilization, with increase of the grain yield, mass of a hundred grains, K level in the grain and number of viable pods. The grain total per pot reached maximum value in combination of the upper limits of each study factor. The K reduced the water deficit effects on the soybean.

Plant-available soil water capacity: estimation methods and implications

A capacidade de agua disponivel no solo para as plantas e definida como o conteudo de agua entre a capacidade de campo e o ponto de murcha permanente e tem vasta aplicacao pratica no planejamento do uso da terra. Em um perfil de Latossolo representativo da regiao do Cerrado, objetivaram-se estudar e comparar metodos de estimativa para o ponto de murcha permanente, empregando os aparelhos de psicrometro WP4-T e a câmara de Richards, utilizando amostras com e sem preservacao da estrutura, bem como para a capacidade de campo, estimando-a pela umidade do solo submetido as tensoes 6, 10 e 33 kPa, e pelo ponto de inflexao da curva de retencao de agua calculado nos modelos de van Genuchten e polinomial cubico. Verificou-se que para o Latossolo em estudo a capacidade de campo determinada no ponto de inflexao apresenta maior valor de umidade em comparacao aos demais metodos e que mesmo nesse ponto sao encontradas diferencas na estimativa em razao do modelo utilizado. Pelo psicrometro WP4-T, valores significativamente menores de umidade foram encontrados para a estimativa do ponto de murcha permanente. Concluiu-se que a capacidade de agua disponivel foi influenciada marcantemente pelo metodo utilizado na estimativa da capacidade de campo e do ponto de murcha permanente, o que precisa ser considerado em virtude da importância pratica desse parâmetro.

Eficiência agronômica de superfosfato triplo e fosfato natural de Arad em cultivos sucessivos de soja e milho

Conduziu-se este estudo, com o objetivo de avaliar os efeitos de doses de adubos fosfatados sobre a cultura da soja e do milho, em cultivos sucessivos. O experimento foi realizado em casa de vegetacao da UFGD, em vasos contendo amostras de 5,5 dm3 de um Latossolo Vermelho Distroferrico argiloso, sendo utilizado como fontes de fosforo (P) o superfosfato triplo (SFT) e o fosfato natural de Arad (FNA). O FNA foi utilizado sob duas formas. Em uma, considerou-se o P total (Arad T) e, em outra, apenas a fracao de P soluvel em acido citrico a 2% (Arad SA), resultando em tres fatores de estudo, cada um em seis niveis de P (0, 56, 112, 224, 336 e 560), expressos em mg dm-3. A soja foi semeada em dezembro de 2006 e ao final do ciclo, efetuou-se a colheita, avaliando-se a produtividade de graos, teores de P na folha e no solo. Apos o cultivo da soja, semeou-se o milho, cuja colheita das plantas ocorreu aos 76 dias apos a semeadura, sendo avaliados a producao de massa seca da parte aerea e teores de P na folha. O indice de eficiencia agronomica foi calculado para ambas as culturas. Conclui-se que, para o primeiro cultivo (soja), o SFT apresentou um melhor desempenho no que se refere a produtividade de graos, quando comparado ao FNA. No cultivo do milho em sucessao a soja, o FNA tendeu a equiparar-se ao SFT nos atributos avaliados.

Seleção precoce de espécies de Passiflora resistente a fusariose

Universidade do Estado de Mato Grosso, Departamento de Genética e Melhoramento de Plantas, Av. Tancredo Neves, 1095 Cavalhada II, CEP 78200-000 Cáceres MT; Instituto Federal de Educação, Ciência e Tecnologia de Mato Grosso, Departamento de solos, Av. dos Ramires, s/n CEP: 78200-000, Cáceres MT; Universidade Federal de Viçosa, Programa de Pós-Graduação em Fitotecnia Campus Universitário, CEP: 36570 900, Viçosa – MG. Autor para correspondência: Sandra da Costa Preisigk (sandrapreisigke@hotmail.com) Data de chegada: 05/02/2017. Aceito para publicação em: 27/04/2017. 10.1590/0100-5405/175390

Aggregate stability by the "high energy moisture characteristic" method in an oxisol under differentiated management

Studies testing the High Energy Moisture Characteristic (HEMC) technique in tropical soils are still incipient. By this method, the effects of different management systems can be evaluated. This study investigated the aggregation state of an Oxisol under coffee with Brachiaria between crop rows and surface-applied gypsum rates using HEMC. Soil in an experimental area in the Upper Sao Francisco region, Minas Gerais, was studied at depths of 0.05 and 0.20 m in coffee rows. The treatments consisted of 0, 7, and 28 Mg ha-1 of agricultural gypsum rates distributed on the soil surface of the coffee rows, between which Brachiaria was grown and periodically cut, and compared with a treatment without Brachiaria between coffee rows and no gypsum application. To determine the aggregation state using the HEMC method, soil aggregates were placed in a Buchner funnel (500 mL) and wetted using a peristaltic pump with a volumetric syringe. The wetting was applied increasingly at two pre-set speeds: slow (2 mm h-1) and fast (100 mm h-1). Once saturated, the aggregates were exposed to a gradually increasing tension by the displacement of a water column (varying from 0 to 30 cm) to obtain the moisture retention curve [M = f (Ψ) ], underlying the calculation of the stability parameters: modal suction, volume of drainable pores (VDP), stability index (slow and fast), VDP ratio, and stability ratio. The HEMC method conferred sensitivity in quantifying the aggregate stability parameters, and independent of whether gypsum was used, the soil managed with Brachiaria between the coffee rows, with regular cuts discharged in the crop row direction, exhibited a decreased susceptibility to disaggregation.