A comparative study of the nutrient status of household waste composted using different starters

The influence of different compost starters on nutrient composition of household waste compost was evaluated under growth chamber conditions. Compost starters investigated were soil only, lime ammonium nitrate (LAN), poultry manure, and fungi only. Fungi used were species of Mucor, Trichoderma, Cephalosporium and Penicillium. Nutrient compost analyses at 4 and 8 weeks showed the household waste compost to be non acidic, and although the type of starter influenced the compost pH, this influence was non significant (

THE EFFECT OF DROUGHT ON ECONOMICALLY OPTIMAL NITROGEN FERTILIZATION RATES OF DRYLAND WHEAT IN THE SUMMER RAINFALL AREA

A quadratic nitrogen response model for dryland wheat with moisture stress dependent coefficients is described and validated. The model was used to estimate the effects of moisture stress on the nitrogen levels corresponding to a maximum yield and an economically optimal yield, respectively. For the range of stress values representative of dryland cropping conditions in South Africa the nitrogen level needed for a maximum yield was largely independent of the stress level. In contrast, the nitrogen level needed for an economically optimal yield increased sharply with increasing moisture stress. The implications of these results with respect to the problem of nitrogen fertilization in semi-arid regions are discussed

Resposta à aplicação e recuperação de enxofre em cultivos de casa de vegetação em solos com diferentes teores de argila e matéria orgânica Responses to sulfur application and recuperation in greenhouse crops in soils with different clay and organic matter content

A dinâmica e a disponibilidade do enxofre têm sido pouco estudadas em relação a outros nutrientes, apesar da sua importância como nutriente à planta. Este estudo teve como objetivo avaliar a resposta de algumas culturas à aplicação de sulfato (S-SO4-2) em solos com diferentes teores de argila e matéria orgânica, bem como avaliar a recuperação de enxofre, através de um balanço deste elemento no solo e na planta. O experimento consistiu de seis cultivos sucessivos (canola, soja, feijoeiro, gergelim, trevo vesiculoso e trigo), em vasos em casa de vegetação, utilizando-se quatro tipos de solos e quatro doses de S-SO4-2, com quatro repetições distribuídas ao acaso. Avaliou-se a produção de matéria seca, o teor e o acúmulo de enxofre absorvido pelas culturas. Amostras de solo foram coletadas na camada de 0-10cm após cada cultivo, para determinação do teor de S-SO4-2 disponível. Dentre as culturas estudadas, somente a canola respondeu à aplicação de S-SO4-2. Para as demais culturas, não houve relação entre os teores de S-SO4-2 da camada de 0-10cm e a produção de matéria seca. Solos com diferentes teores de argila e matéria orgânica tiveram comportamento similar em relação à resposta das culturas à fertilização com enxofre; entretanto, a disponibilidade deste nutriente foi maior nos solos mais argilosos.<br>The sulfur (S) dynamic and availability is less studied than others nutrients, even though S is an essential nutrient for crops production. This study was carried out to evaluate the crop responses to S-SO4-2 application in different soils and to study S recuperation by balancing it in soil and plants. The study was composed by a greenhouse experiment with six successive crops (canola, soybean, black bean, sesame, clover and wheat) using four soils and four S-SO4-2 levels (0, 5, 10 and 20mg kg-1) to evaluate immediate and residual effect of S-SO4-2 application. Soil samples were taken from 0-10 cm layer before and after each crop and analyzed for S-SO4-2. It was evaluate the dry matter production and S-SO4-2 absorbed by plants. Only canola responded to sulphur application. Soybean, black bean, sesame, clover and wheat did not response to sulfur application. There was not observed correlation between soil S-SO4-2 available in 10cm topsoil and crop yields. Soils with different clay and organic matter content showed similar behavior of crop response to sulfur application. The increase of S-SO4-2 availability with fertilization was greater in soils with more clay content