Ismail Soares

Crescimento e absorção de nutrientes por mudas de gravioleira

The objective of the research was to determine growth and nutrient absorption rates of soursop (Annona muricata L.) during seedling phases. Seeds of soursop after germination were transferred to polyethylene bags filled with 5 dm3 of a 3:1 (v/v) mixture of surface soil:organic mineral soil. Fifteen days after seedling transplanting and each fifteen days intervals up to 195 days, five seedlings were randomized taken for height, stem diameter and nutrient absorption evaluation. Seedlings growth was initially slow up to 105 days, and only 27% of dry matter were produced. Mineral nutrient absorption increased with plant age and 67% was accumulated from 105 to 195 days period in the following order K>N>Ca>Mg>P and Fe>Zn>Mn>Cu.

Yield performance of upland rice cultivars at different rates and times of nitrogen application

O N e o nutriente de maior importância para a produtividade do arroz (Oryza sativa L.). Este trabalho teve por objetivo avaliar a resposta de cultivares de arroz de terras altas em funcao de diferentes doses e epocas de adubacao nitrogenada. Utilizou-se o delineamento experimental em blocos casualizados com parcelas subsubdivididas, com quatro repeticoes. Foram estudadas cinco cultivares de arroz (BRS MG Curinga, BRS Monarca, BRS Pepita, BRS Primavera e BRS Sertaneja), tres epocas de aplicacao de N (100 % na semeadura; 50 % na semeadura e 50 % no perfilhamento; e 100 % no perfilhamento) e quatro doses de N (0, 50, 100 e 150 kg ha-1). As cultivares avaliadas responderam ao incremento de doses e a epoca de aplicacao de N, destacando-se BRS Primavera e BRS Sertaneja como as mais produtivas quando as doses de N foram distribuidas 50 % na semeadura e 50 % no perfilhamento, enquanto a cultivar BRS Monarca apresentou a melhor resposta a adubacao nitrogenada quando todo o N foi aplicado no perfilhamento.

Nitrato de amônio ocluído em zeólita 4A: lixiviação e absorção de nitrogênio no cultivo de milho

Systematic studies were undertaken in the intra zeolitic media to better understand the ability of zeolite type LTA in occluded nitrogen used in fertilizer and soil conditioning. We have measured the dry matter production from the cultivation of corn in a greenhouse for about 40 days, and also the amounts of nitrogen absorbed, retained and lost by leaching. The dry matter production in the cultivation with different concentrations of nitrogen occluded in the zeolite, was more efficient than the traditional fertilizer, which demonstrated better use of nitrogen to reduce leaching losses, which implies a possible reduction of costs for nitrogen.

Produção de serapilheira e ciclagem de nutrientes na cultura do cajueiro anão precoce

This study aimed to (a) to evaluate the biomass production from the crown of the young dwarf cashew, clone CCP 76, at 2, 3, 8 and 9 years of culture implantation, (b) to determine the rate of leaf decomposition and (c) to quantify nutrient contribution potentially available in the biomass to be recycled into the soil. The research was conducted at the Experimental Field of Curu, in Paraipaba - CE, from December, 2003 to January, 2005. The treatments consisted of orchards with trees of 2, 3, 8 and 9 years of plantation, distributed in a completely randomized design with eight replications. Litter was collected using 1 m2 collectors with 1 mm2 mesh place 40 cm above the soil surface. After sampling, the material was sorted out into portions of leaves, branches, inflorescence, peduncle and nut, oven dried and weighed. In the leaf portion, the compositions of N, P, K, Ca, Mg, S, Na, Cu, Fe, Mn and Zn were determined. Leaves ready to fall were collected from each plant to determine their decomposition rate and 12 g of this material was stove dried, and placed in 20 cm x 20 cm nylon bags and 2 mm mesh which were distributed on the soil surface and collected after 112, 233 and 369 days. In each collection, the material was oven dried and the remaining nutrient biomass (N, P, K, Ca, Mg, S, Na, Cu, Fe, Mn and Zn) was determined. The 8- and 9- year- old plants deposited greater quantities of litter during the experimental period and showed greater potential for nutrient recycling. During the experimental period it was generally observed that the decomposition process was fast in the first four months, remaining slow until the end of the observation period. Most of the nutrients in the cashew tree were released in the first four months of leaf composition.