Propriedades químicas de um latossolo vermelho de cerrado cultivado com algodão sob diferentes preparos e adubações

The high rate of mineralization of organic matter on savannah soils, which is reached fi ve times faster than in temperate regions, leads us to the challenge of electing the best system of management that maintains and/or increase it in soil, guaranteeing its quality and sustainability. In this sense the present research aimed to study the effects of green, organic and mineral manure on the chemical properties on the chemical properties of an Oxisol, on Savannah area, cultivated with cotton (Gossypium hirsutum) under conventional tillage and no-tillage in the pasture fi eld (Brachiaria decumbens) for 20 years. The experimental design was a randomized block design with split plots. The main plots consisted of two treatments: conventional tillage and no-tillage, and the subplots of six treatments: control (no fertilizer), mineral fertilizer recommended for the crop, according to the soil chemical analysis, organic fertilizer (cattle manure - 20 t ha-1), organic fertilizer (cattle manure - 20 t ha-1) + 1/2mineral fertilization recommended according to the analysis of soil, green manure-1 (Crotalaria juncea) and green manure-2 (Pennisetum americanum). There were studied the following soil chemical properties: P, OM, pH, K, Ca, Mg, Al, Al + H, S, exchange capacity cations and base saturation. The soil samples for the analysis were performed on layers of 0,00-0,05 m, 0,05-0,10 and 0,10-0,20 m. Then it came the following conclusions: the fertilization interfere in soil chemical properties and the preparation did not interfere, the cattle manure and its association with the mineral fertilizer caused increasing level elements in the soil, Crotalaria juncea and Pennisetum americanum did not infl uence on soil chemical properties

Monitoring and evaluation of need for nitrogen fertilizer topdressing for maize leaf chlorophyll readings and the relationship with grain yield

The study was carried out for two years in maize in succession to the wheat using no tillage system in a distroferric Red Latosol (Hapludox). Methods of management nitrogen fertilizer (120 kg ha-1) with ammonium sulphate were studied; the fertilizer was applied in maize sowing or in maize topdressing, and N with previous application in wheat sowing. In addition, leaf chlorophyll reading was used as an indicator for the need for topdressed nitrogen fertilizer. Nitrogen supply index (NSI) was shown to be effective at predicting need for topdressed nitrogen fertilizer for maize. The application of N improved the yield of the maize independent of the management system. The flowering stage was carried out at the appropriate time in order to estimate the nitrogen nutrition state and yield of maize using the relative chlorophyll level (RIC)

Manejo da adubação nitrogenada e influência no crescimento da aveia preta e na produtividade do milho em plantio direto = Management of nitrogen fertilization in the growth of black oat and corn yield in a no-tillage system

A aveia preta é responsiva à adubação nitrogenada, a qual propicia aumento de biomassa e acúmulo de N, o qual poderá ser aproveitado pelo milho em sucessão. O trabalho foi realizado em Campo Mourão, Estado do Paraná, e teve como objetivo avaliar a resposta da aveia àadubação nitrogenada e a produtividade do milho cultivado em sucessão. Os tratamentos consistiram na aplicação de nitrogênio (120 kg ha-1), tendo como fonte o sulfato de amônio, como a seguir: T1: (24-90-30); T2 (0-90-30); T3 (144-0-0); T4: (0-0-0), onde a adubação foi feita respectivamente na semeadura da aveia preta (SA), em pré-semeadura do milho, na aveia dessecada (PS) e na semeadura do milho (SM). No tratamento 1, a aveia recebeu somente a adubaçãonitrogenada na semeadura (24 kg ha-1) e no tratamento 2, a aveia não foi adubada; somente o milho recebeu adubação com N. No tratamento 3, a aveia recebeu uma adubação nitrogenada básica na semeadura (24 kg ha-1), mais 120 kg de N ha-1, antecipado do milho, o que fez um total de144 kg N ha-1. Os resultados permitiram concluir que, durante dois anos, aveia adubada com 144 kg ha-1 de N na semeadura possibilitou maior produção de massa seca, a qual influenciou positivamente naabsorção de N e na produtividade do milho; não foi observada diferença na produtividade do milho submetido à adubação nitrogenada no início do cultivo (120 kg ha-1) ou quando aplicado todo N nasemeadura da aveia adubada (144 kg ha-1).The black oat is a crop that responds well to nitrogen fertilization,resulting in biomass increase and accumulation of N, which can then be used in succession by corn. The experiment was accomplished in Campo Mourão, Paraná state, over two agricultural years andthis study had as its objective to evaluate the response of oats to nitrogen fertilization, as well as the yield of corn cultivated in succession. The treatments consisted of nitrogen application (120 kg ha-1) on the oats, through ammonium sulfate, as follows: 24-90-30; 0-90-30; 144-0-0; 0-0-0; these sequences of numbers correspond to N applied in the sowing of black oats (SA), N in pre-sowingof corn (PS), and N in the sowing of corn (SM). In the treatment one, the oat received only the nitrogen fertilizer in sowing of 24 kg ha-1 and in the treatment two, the oat was not fertilized, but the corn received it. In the treatment three, the oat received a nitrogen fertilizer basic in sowing of 24 kg ha-1, as well it received 120 kg N of corn, that made of 144 kg N ha-1. The results led to theconclusion that the oats fertilized with 144 kg ha-1 of N during sowing obtained a larger production of dry mass, as well it increased the N content and corn yield; the corn has not difference of yieldwhen submitted to the nitrogen fertilizer in the beginning of the cultivation (120 kg ha-1) or when the fertilizer was applied all in the oats sowing (144 kg ha-1)