• Authors:
    • de Freitas Konrad, M. L.
    • Guimaraes, C. M.
    • Pedroso, C.
    • Scian Meneghin, M. F.
    • Gerosa Ramos, M. L.
  • Source: Bioscience Journal
  • Volume: 28
  • Issue: 1
  • Year: 2012
  • Summary: Growth of agriculture and livestock can result in opening new areas for planting and has increased research to obtain sustainable production systems with lower impact and soil degradation. Soil management and cover plant alters their properties, mainly, microbiological one, leading changes on functional microorganisms density. The aim of this work was to evaluate the effect of management systems and different planting systems on density of functional groups of microorganisms in cerrado soil. Soil samples were collected in two layers (0-5cm e 5-20cm) and two periods (dry and wet season). The treatments studied were: no-tillage (NT); no-tillage with crop rotation (NTCR); conventional tillage (CT); conventional tillage with crop rotation CTCR) and native Cerrado (mesophytic forest). Native Cerrado showed higher microbial density at both layers and periods of evaluation. In general, the treatments NTCR and NT had the highest microbial density at superficial layers. The results of linear correlation between functional groups of microorganisms and chemical soil varied among tillage system. It was concluded that cerrado soil presented higher microbial density and microbial density was similar among soil management at dry period.
  • Authors:
    • Diniz, A. A.
    • Oliveira, F. R. A. de
    • Rebouças, J. R. L.
    • Dias, N. da S.
    • Andrade Filho, J.
    • Sousa Neto, O. N.
    • da S. Dias, N.
    • de Oliveira, F. R. A.
  • Source: Revista Brasileira de Engenharia Agrícola e Ambiental
  • Volume: 16
  • Issue: 2
  • Year: 2012
  • Summary: An experiment was conducted at the Universidade Federal Rural do Semi-arid in Mossoro, RN with the aim of evaluating the behavior of cotton ( Gossypium hirsutum L. race latifolium Hatch) 8H cultivar, in terms of growth when irrigated with treated domestic sewage. The experimental design was in randomized blocks with split plots and in plots were tested dilutions of wastewater [25% - T1, 50% - T2, 75% - T3 and 100% of wastewater - T4 and supply water with mineral fertilizer - T5] in two soils of contrasting textures. Irrigation with wastewater significantly influenced the growth of cotton plants, the rate of emergence, the germination percentage, plant height, stem diameter and leaf area, growing linearly until an optimal dose, as the proportion of use of domestic effluent. The positive effect of the accumulation of nutrient in soil applied by fertigation on the variables studied is also highlighted. The irrigation with treated wastewater can offset conventional fertilization of cotton.
  • Authors:
    • Foratto, L. C.
    • Salomão, L. C.
    • Quaggio, J. A.
    • Boas, R. L. V.
    • Souza, T. R. de
  • Source: Pesquisa Agropecuária Brasileira
  • Volume: 47
  • Issue: 6
  • Year: 2012
  • Summary: The objective of this work was to evaluate nutrient dynamics in soil solution after fertigated application of nitrogen, phosphorus, and potassium to orange trees. The experiment was carried out from September 2007 to October 2009, in 'Valencia' and 'Hamlin' orange orchards grafted onto citrumelo 'Swingle' rootstock. Five doses of N, P 2O 5 and K 2O (0, 25, 50, 100 and 200% of the recommended dose) were evaluated. Soil solution was extracted from 30 and 60 cm soil depths using extractors with porous cups. Eleven evaluations were done during the experimental period, with extractions beginning 12 hours after fertigation. Increasing nutrient doses decreased pH (pH-3.5, at the highest dose), and increased electrical conductivity (CE-1.5 dS m -1, at the highest dose) and the amounts of NH 4, NO 3, P, K, Mn, and Zn in the soil solution, in both sampled depths. In the months with heavier rainfall, there was nutrient potential losses by leaching, since higher concentrations of NO 3, K, and B were observed at the 60 cm soil depth. Soil solution analysis, obtained by extractors with porous ceramic cups, can be considered an auxiliary tool for monitoring and assessing nutrient availability to plants.
  • Authors:
    • Tolentino, J. B.
    • Coelho, R. D.
    • Vellame, L. M.
  • Source: Revista Brasileira de Fruticultura
  • Volume: 34
  • Issue: 1
  • Year: 2012
  • Summary: The total citrus area irrigated in Brazil has increased over the decades. The main cause of this increasing is due to the use of rootstocks tolerant to Citrus Sudden Death however they are less tolerant to drought than Rangpur lime. This research aims to study the influence of rootstock and soil type on transpiration of young plants of Valencia orange. The experiment was conducted in a greenhouse at the Department of Biosystems Engineering, ESALQ/USR Orange seedlings were planted in boxes of 500 L. It was determined simultaneously sweating of 20 plants through thermal dissipation probes (sap flow). It was monitored solar radiation, relative humidity and air temperature sensors were installed to 2 m tall at the center of the greenhouse. The reference evapotranspiration (ETo PM) was calculated by the standard method suggested by FAO. According to these results it is concluded that plant transpiration of Valencia oranges are influenced not only by the type of rootstock but also by leaf area growth and phenological stage, and its relationship with ETo pM is not linear in the whole range of evaporative demand of the atmosphere.
  • Authors:
    • Folegatti, M. V.
    • Paulino, J.
    • Coelho, R. D.
    • Zolin, C. A.
  • Source: Engenharia Agrícola
  • Volume: 32
  • Issue: 3
  • Year: 2012
  • Summary: Although several studies have been conducted to evaluate the uniformity of water application under center pivot irrigation systems, there are few studies concerning the economic perspective of such coefficient. The aim of this study is to present a methodology to accomplish an economic analysis as support for the decision-making to retrofit emitters in center pivot irrigation systems, and to attribute an economic meaning to the uniformity coefficient of water application taking into account the response function productivity to the amount of water applied and the sale price of the crops. In the hypothetic calculation example considering the variation of revenue of potato crop under center pivot irrigation system, it was verified that the area with uniformity coefficient of water application of 90% brought an income increase of BR$ 1,992.00, considering an area about 1,0 ha. Thus, it can be concluded that the methodology presented has met the objectives proposed in the study and made it possible to attribute an economical meaning to the coefficient of water uniformity application.
  • Authors:
    • Begue, A.
    • Dubreuil, V.
    • Meirelles, M.
    • Arvor, D.
    • Shimabukuro, Y. E.
  • Source: Applied Geography
  • Volume: 32
  • Issue: 2
  • Year: 2012
  • Summary: The Amazonian state of Mato Grosso is the main production area for soybeans in Brazil and contains 31.3% of the national production as of 2009. The rapid evolution of the agricultural systems in this area shows that the region is experiencing a rapid agricultural transition. In this paper, we broke down this transition process into three steps: crop expansion, agricultural intensification and ecological intensification. We used remote sensing products to develop and compute satellite-derived indices describing the main agricultural dynamics during the cropping years from 2000-2001 to 2006-2007. Our results indicated that Mato Grosso is continuing to expand its agricultural sector, with a 43% increase in the net cropped area during the study period. Although this expansion mainly occurred in the cerrado ecoregion until the early 2000s, the forest ecoregion is experiencing expansion at this time. We observed that 65% of the crop expansion in Mato Grosso from 2000 to 2006 occurred in this ecoregion. However, we did not identify this crop expansion as the major driver of deforestation in Mato Grosso because only 12.6% of the cleared areas were directly converted into croplands. Agricultural intensification also evolved rapidly, as the proportion of the net cropped area cultivated with double cropping systems harvesting two successive commercial crops (i.e., soybean and corn or soybean and cotton) increased from 6% to 30% during the study period. Finally, we found that ecological intensification occurred because the region's farmers planted a non-commercial crop (i.e., millet or sorghum) after the soybean harvest to prevent soil erosion, improve soil quality, break pest cycles, maintain soil moisture and set the conditions for high-quality no-tillage operations. In 2006-2007, 62% of the net cropped area was permanently covered by crops during the entire rainy season. This practice allowed the farmers to diversify their production, as shown by the positive evolution of the Area Diversity Index. Future scholars can use the method proposed in this paper to improve their understanding of the forces driving the agricultural dynamics in Mato Grosso.
  • Authors:
    • Vogt, G. A.
    • da Veiga, M.
    • Balbinot Junior, A. A.
    • Spagnollo, E.
  • Source: Ciência Rural
  • Volume: 42
  • Issue: 3
  • Year: 2012
  • Summary: The objective of this study was to evaluate in the fifth year of experimentation, the effect of winter soil uses on residual straw on the soil, physical and chemical soil attributes and grain yield of common bean cultivated in succession. An experiment was carried out in the North Plateau of Santa Catarina State, Brazil, from May 2006 to April 2011. Five winter soil uses were investigated: 1) multicropping with black oat + ryegrass + common vetch without grazing (multicropping cover); 2) the same multicropping, with grazing and 100kg ha(-1) of nitrogen year(-1), applied during the growing period (pasture with N); 3) the same multicropping, with grazing and without nitrogen fertilization (pasture without N); 4) oil seed radish, without grazing (oil seed radish); and 5) natural vegetation, without grazing (fallow). In the fifth year of experimentation, multicropping cover treatment inputted greater straw on the soil, but it was not observed expressive differences in soil attributes among the five winter soil uses. Cover crops, annual pasture and winter fallow did not affect the grain yield of common bean cultivated in succession.
  • Authors:
    • Barbosa, A. L.
    • Sousa, L. N.
    • Silva, A. E. V. N.
    • Araujo, G. G. L. de A.
    • Pereira, L. G. R.
    • Menezes, D. R.
    • Barreto, V. N. S.
    • Costa, J. M. da S.
    • Moreira, R. F.
  • Source: Revista Brasileira de Saude e Producao Animal
  • Volume: 13
  • Issue: 1
  • Year: 2012
  • Summary: This work aimed to evaluate a utilization of the Salt brush ( Atriplex nummularia) irrigated with residue from desalination as an alternative to Caipira French chickens' fattening diet. Hundred twenty chickens (60 males and 60 females), 28 day old, were selected individually away and by body weight and were distributed in a complete randomized design with four treatments, five repetitions and six chickens by experimental unit. Experimental diets were isonutritious and formulated by cassava hay (CH), Atriplex hay (AH), corn grain and soybean meal. It was used four treatments: 0%, 35%, 65% and 100% with replacement of CH by the AH in the base feed. There was no significant difference amount the intake of dry matter, crude protein and gross energy in relation to the replacement of CH by the AH who presents media of 133.9 g/chicken/day, 19.8 g/chicken/day and 543.3 Kcal/chicken/day respectively. The feed gain ratio of the diets tested had linearly increased. With a 17.7% replacement of CH by AH can be obtained maximum gains of 432.4 g and 14.4 g/day, respectively for total and daily average gain. The replacement of CH by the AH in the range from 46.4 to 50% showed better results for carcass weight and economic value in diets.
  • Authors:
    • Pitelli, R. A.
    • Bianco, M. S.
    • Carvalho, L. B.
    • Bianco, S.
  • Source: Planta Daninha
  • Volume: 30
  • Issue: 1
  • Year: 2012
  • Summary: Soybean is one of the main crops in Brazil, but its productivity is very affected by weed competition. Two experiments were carried out in Jaboticabal, SP, Brazil, under greenhouse conditions to determine the accumulation and distribution of dry mass and macronutrients in soybean cv. BR-16, from October 2000 to February 2001, and Solanum americanum plants, from January to May 1995. Plants were grown in seven liter pots filled with river sand substrate and were daily irrigated with nutrient solution. The treatments were constituted by the times of samplings carried out at 14 day intervals, starting 21 days after emergence (DAE). Soybean evaluation was extended to 161 DAE, while S. americanum was extended to 119 DAE. The point of maximum theoretical accumulation of dry mass in soybean occurred at 104 DAE (35.00 g per plant) while for S. americanum, it occurred at 143 DAE (179.62 g per plant). From emergence until 49 and 63 DAE, leaves showed higher participation in dry mass accumulation of soybean and S. americanum, respectively. After these periods, an inversion could be observed, with leaves being surpassed by stems for the weeds, and by stems and later, by reproductive structures, for the crop. Macronutrient uptake rate reached higher values between 69 to 87 DAE for soybean and between 105 to 119 DAE for S. americanum. Considering the mean inflexion point values observed in soybean crop, at 75 DAE, it can be evidenced that one soybean plant theoretically accumulated 23.90 g of dry mass, 564.40 mg of N, 7.10 mg of P, 490.80 mg of K, 487.00 mg of Ca, 156.60 mg of Mg and 36.00 mg of S, while one S. americanum plant theoretically accumulated 33.75 g of dry mass, 875.96 mg of N, 88.46 mg of P, 983.54 mg of K, 647.60 mg of Ca, 100.93 mg of Mg, and 42.15 mg of S.
  • Authors:
    • Heinz, R.
    • Garbiate, M.
    • Tadeu Vitorino, A.
    • Viegas Neto, A.
    • de Sousa Mota, L.
    • Pereira Correia, A.
  • Source: Ciencia Rural
  • Volume: 41
  • Issue: 9
  • Year: 2011
  • Summary: This study aimed to evaluate the decomposition and nutrient release from crop residues of fodder radish and crambe in the implementation of no-tillage system. The experiment was conducted in a Distroferric Red Latossol with 762g kg(-1) of clay. The experimental design was randomized blocks with four replications. The treatments were applied in split plots, considering the species of cover crops (radish and crambe) as the main plots and harvest dates of decomposition bags (0, 15, 30, 45, 60, 75 days after management) as subplots. The cover crops were treated 60 days after management, in full bloom. Radish presented a dry mass production of 5586kg ha(-1) and crambe of 2688kg ha(-1). The kinetics of residue decomposition had a behavior similar to the dynamics of nutrient release, with an initial rapid phase followed by a slower one. The K, P and Mg are released more quickly for subsequent crops. The increased speed of nutrients release by crops occurred around 15 days after the biomass management.