Resposta do milho ao modo de aplicação e doses de nitrogênio, em sistema de semeadura direta

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)

Parcelamento da adubação nitrogenada em cobertura no feijoeiro em sucessão ao milho e Urochloa ruziziensis em sistemas plantio direto

Pós-graduação em Agronomia (Produção Vegetal) - FCAV

Avaliação de sistemas de produção e aplicação superficial de corretivos em plantio direto

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

Corn productivity in function of surface application of lime in differents management systems and cultural preparation

The evaluation of technologies employed at the agricultural production system such as crop rotation and soil preparation, both associated with crop-livestock integration, is crucial. Therefore, the aim of the present study was to evaluate the incorporation of lime for three no-tillage systems and cultural managements in system of crop-livestock integration, with emphasis on corn grain yield. The experiment was conducted from January 2003 to April 2005 at Selvíria city, MS, in Dystroferric Red Latosol, clay texture. The experimental design was randomized blocks with split plots consisted of three main treatments, aimed the soil physics conditioning and the incorporation of lime: PD - No-no-tillage; CM - minimum no-tillage, and PC - conventional no-tillage; and of two secondary treatments related to the management: rotation and crop succession, with four replications. Data on agronomic traits of maize were analyzed: plant height, stem diameter, height of the first spike insertion, 100 grains weight and grain yield. The results showed that the maize produced under the system of crop-livestock integration is quite feasible, showing that grain yields are comparable to averages in the region and the different soil physical conditioning and incorporation of lime did not influence the corn yield as well as the cultural managements, rotation and succession, did not affect the maize crop behavior after two years of cultivation.

Doses e épocas de aplicação de nitrogênio: Influência na relação C/N da palhada no desenvolvimento e produtividade do milho em sistema plantio direto

The objective of this research work was to evaluate the effects of doses and time of application of N on the C/N ratio of the straw cover and on the growth and productivity of maize plants growing in a no tillage system. The experiment was carried out at the Experimental Farm of the College of Agriculture of the São Paulo State University (UNESP) on its campus of Botucatu, state of São Paulo, Brazil. The treatments were distributed in the field according to a randomized complete block design in a split plot arrangement. The treatments consisted of four doses of N (0, 20, 40, and 60 kg ha-1 ) applied to oat crop and N doses (60, 80, 100, and 120 kg ha-1 ) sidedressed to corn. The development and productivity of the maize crop in a no-tillage system were found to be dependent of the C/N ratio and the straw cover. The response of the maize plants to the early application of N is dependent on doses and time of application.

Soil organic matter as a function of nitrogen fertilization in crop successions

A interdependência dos ciclos de C e N reflete-se nos teores de matéria orgânica do solo (MOS). em um delineamento experimental em blocos casualizados, com parcelas sub-subdivididas, tendo como tratamento principal cinco doses de nitrogênio de cobertura na cultura do milho (0; 60; 120; 180 e 240 kg ha-1 de N), como tratamento secundário, as sucessões milho-milho e soja-milho, e como sub-subtratamento, duas profundidades de amostragem (0 a 0.2 e 0.2 a 0.4 cm), avaliaram-se os teores de MOS e de C orgânico nas frações solúvel em água (C-SA), ácidos húmicos (C-AH), ácidos fúlvicos (C-AF) e humina (C-H), por meio do método clássico de fracionamento químico, em um Latossolo Vermelho eutrófico, de textura argilosa. A adubação nitrogenada não afetou os teores de MOS, mas favoreceu a síntese de compostos da fração C-AH. Houve efeito quadrático das doses de N nos teores de C-SA e de C-AF na sucessão milho-milho. A sucessão soja-milho resultou em maiores teores de MOS e de C orgânico na fração humina.

Crop sequences in no-tillage system: effects on soil fertility and soybean, maize and rice yield

Os resíduos vegetais das culturas, ao se decomporem, alteram os atributos químicos do solo e, como consequência, influenciam a produtividade das culturas em sucessão. O objetivo deste trabalho foi avaliar os atributos químicos do solo e a produtividade das culturas de soja, milho e arroz, cultivadas no verão, em sucessão a culturas de inverno em semeadura direta. O experimento foi realizado em Jaboticabal-SP (48 ° 18 ' 58 '' W e 21 ° 15 ' 22 '' S), em um Latossolo Vermelho eutrófico. O delineamento experimental foi em blocos ao acaso, no esquema em faixas, com três repetições. Os tratamentos foram constituídos pela combinação de quatro sequências de culturas de verão (monoculturas de milho e soja e rotações soja/milho e arroz/feijão/algodão) com sete culturas de inverno (milho, girassol, nabo forrageiro, milheto, guandu, sorgo e crotalária). Os cultivos iniciaram-se em 2002. Após o manejo das culturas de inverno e antes da semeadura das culturas de verão do ano agrícola 2006/2007, foram coletadas amostras de solo nas camadas de 0-2,5; 2,5-5,0; 5-10; 10-20; e 20-30 cm. Nas amostras de solo, foram determinados: teores de matéria orgânica, pH, teores de P (resina), K, Ca e Mg trocáveis e acidez potencial (H + Al). As sequências de verão rotação soja/milho e milho em monocultura proporcionaram no solo menores teores de matéria orgânica na camada de 0-10 cm e de P do solo na camada de 0-20 cm. Na sequência de verão arroz/feijão/algodão, maiores teores de K foram proporcionados pelas culturas de inverno crotalária e nabo forrageiro, na camada de 0-10 cm, e milheto, na de 0-2,5 cm. Crotalária, milheto, nabo forrageiro e sorgo, cultivados no inverno, proporcionaram maiores teores de matéria orgânica no solo na camada de 0-30 cm. Maiores teores de P no solo foram proporcionados pela crotalária, na camada de 0-2,5 cm, e pelo nabo forrageiro, na de 0-5 cm. Maiores produtividades de soja, como monocultura de verão, foram obtidas após nabo forrageiro e crotalária e, quando em rotação com milho no verão, após nabo forrageiro, crotalária e milheto. Maiores produtividades de milho foram obtidas após nabo forrageiro, milheto e guandu, e menor produtividade de arroz foi obtida após sorgo.

Nitrogen Supply for Cover Crops and Effects on Peanut Grown in Succession under a No-Till System

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

Dynamics of aggregate stability influenced by soil management and crop residues

The type of tillage and crop systems used can either degrade or cause a recovery of the structure of agricultural soils. The objective of this study was to determine the structural stability of the soil using mean weight diameter (MWD) of soil aggregates in three different periods of a succession of crops consisting of beans/cover plants/maize under no tillage (NT) and conventional tillage (CT) management systems. Soils were sampled at 0- to 5-cm and 5- to 15-cm depths in three periods (P1, P2, P3): 1) November 2002 (spring/summer), 2) April 2003 (beginning of autumn), and 3) December 2003 (end of spring/beginning of summer). Aggregate stability was determined by wet sieving. The effects of the tillage systems, vegetal residues, and sampling depths on the structural stability of the aggregates were assessed and then related to organic matter (OM) contents. Aggregate stability showed temporal variation as a function of OM contents and sampling period. No tillage led to high MWD values in all study periods. The lowest MWD values and OM contents were observed 4 months after the management of the residues of cover plants. This finding is consistent with the fact that at the time of the samplings, most of the OM had already mineralized. The residues of sunn-hemp, millet, and spontaneous vegetation showed similar effects on soil aggregate stability.

MINERAL NITROGEN SUBSTITUTION BY CHICKEN LITTER IN SUCCESSION OAT/CORN

The constant search for sustainability of production systems have driven research to find alternatives to the problems arising from the intensified use such systems. In this context the present work aimed study the effects of substitution of mineral nitrogen by chicken litter in oat and corn crop in succession and the chemical characteristics of soil. The study was conducted during the period May 2009 to March 2010 in area of Oxisol. The design was of randomized block with four replications. The six treatments were obtained by a combination of different amounts of chicken litter (0, 1500, 3000, 4500, 6000 and 7500 kg ha(-1)) applied 30 days before the sowing of oats combined with the mineral nitrogen applied in coverage in corn (311.1, 257.8, 202.2, 148.9, 95.6, 42.2 kg ha(-1) of urea), for the total supply of 140 kg ha(-1) of nitrogen (N). The application of poultry litter in oat promotes increased the production of dry matter, and content and accumulation of N. The mineral nitrogen substitution by chicken litter increases the yield of corn crop. The use of poultry litter alters the chemical properties of soil, increasing the levels of organic matter, exchangeable Al and acidity potential. However lowers the pH, K, Ca, Mg, sum of bases and base saturation.

Sistemas de cultivo antecessores e doses de nitrogênio em cobertura no feijoeiro em plantio direto = cover crop systems and nitrogen topdressing on common bean in no tillage

The objective of this work was to evaluate the grass cover crop production in crop systems involving maize and Urochloa ruziziensis, and the influence of topdressing nitrogen rates in the yield and agronomic efficiency on common-bean cultivated in succession in no-tillage. The experiments were conducted in Jaboticabal-SP, in a eutrophic red latosol, in the second year of no-tillage system implementation. The IPR 139 cultivar was used in split plot design with three replications, in randomized block. The plots had been composed for three crop systems in the summer season, with maize exclusive, maize intercropped with U. ruziziensis and U. ruziziensis exclusive. The subplots had been constituted for five nitrogen rates (0, 40, 80, 120 and 160 kg ha(-1)), applied as topdressing at V4-4 in irrigated common-bean cultivated in the winter-spring season. The use of U. ruziziensis in crops systems, exclusive or intercropped with maize favors the grass cover crop production sufficiently to total soli surface covered, possibility similar grain yield compared to maize exclusive. The topdressing nitrogen application doesn't affect the common-bean yield in succession to maize and U. ruziziensis intercropped. The increase of nitrogen rates in common-bean in succession to maize exclusive improves the yield, although decreases the agronomic efficiency.

The effects of the coexistence of weed communities on table beet yield during early crop development

Objetivando avaliar efeitos de períodos de infestação inicial na comunidade infestante e na produtividade da beterraba em sistema de semeadura direta e transplantio, conduziu-se um experimento em delineamento de blocos casualizados, esquema fatorial 2 x 13. Métodos de semeadura direta e transplante de mudas foram avaliados dentro de 13 períodos semanais crescentes de infestação. Importância relativa, densidade e matéria seca acumulada pelas plantas daninhas foram analisadas por regressão não-linear, assim como produtividade e estande da cultura de beterraba, que foram submetidos à análise de variância. Amaranthus viridis, Coronopus didymus, Cyperus rotundus, Digitaria nuda, Galinsoga parviflora e Nicandra physaloides foram as plantas daninhas mais importantes, destacando-se C. didymus. O acúmulo de matéria seca das plantas daninhas foi maior na cultura em semeadura direta, embora a densidade de plantas daninhas tenha sido mais alta em sistema de transplantio. A produtividade da beterraba transplantada foi maior que a da semeadura direta no tratamento livre de plantas daninhas. A convivência das plantas daninhas com a cultura pode permanecer por quatro e sete semanas depois da semeadura/transplantio, respectivamente, antes de reduzir a produtividade. A cultura em sistema de semeadura direta foi mais susceptível à interferência das plantas daninhas que a cultura sob sistema de transplantio.

Geostatistical analysis of the spatial distribution of Rotylenchulus reniformis on cotton cultivated under crop rotation

The spatial distribution of Rotylenchulus reniformis on cotton cultivated in crop rotation with sorghum-peanut-velvetbean was studied using geostatistics. The experimental field, which had been continuously cropped with cotton for 20 years, comprised two 32 x 48 m-grids, each divided in sixty-four 4 x 6 in sampling plots. For all crops, 300 cm(3) soil samples were taken at the center of each plot at crop germination (Pi) and again at harvest (Pf), from which the numbers of nematodes were determined. The results revealed that the spatial distribution of R. reniformis was highly aggregated and with the aid of geostatistical techniques the nematode intensities were mapped and the risk areas accurately identified. Consequently, geostatistics is here considered a useful tool for planning nematode control strategies, particularly in precision agriculture.

Analysis of the Priestley-Taylor alpha parameter for a bean crop

This work deals with the Priestley-Taylor model for evapotranspiration in different grown stages of a bean crop. Priestley and Taylor derived a practical Formulation for energy partitioning between the sensible and latent heat fluxes through the a parameter. Bowen ratio energy balance (BREB) was carried out for daily sensible and latent heat flux estimations in three different crop stages. Mean daily values of Priestley-Taylor a parameter were determined for eleven days during the crop cycle. Diurnal variation patterns of a are presented for the growing, flowering and graining periods. The mean values of 1.13 +/- 0.33, 1.26 +/- 0.74, 1.22 +/- 0.55 were obtained for a day in the growing, in the flowering and for graining periods, respectively. Eleven days values of a are shown and gave a mean value of 1.23 +/- 0.10 which agree on the reported literature.

Validation of the Deardorff model for estimating energy balance components for a sugarcane crop

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)