• Authors:
    • Zhang,K.
    • Castanho,A. D. de A.
    • Galbraith,D. R.
    • Moghim,S.
    • Levine,N. M.
    • Bras,R. L.
    • Coe,M. T.
    • Costa,M. H.
    • Malhi,Y.
    • Longo,M.
    • Knox,R. G.
    • McKnight,S.
    • Wang,J. F.
    • Moorcroft,P. R.
  • Source: Global Change Biology
  • Volume: 21
  • Issue: 7
  • Year: 2015
  • Summary: There is considerable interest in understanding the fate of the Amazon over the coming century in the face of climate change, rising atmospheric CO 2 levels, ongoing land transformation, and changing fire regimes within the region. In this analysis, we explore the fate of Amazonian ecosystems under the combined impact of these four environmental forcings using three terrestrial biosphere models (ED2, IBIS, and JULES) forced by three bias-corrected IPCC AR4 climate projections (PCM1, CCSM3, and HadCM3) under two land-use change scenarios. We assess the relative roles of climate change, CO 2 fertilization, land-use change, and fire in driving the projected changes in Amazonian biomass and forest extent. Our results indicate that the impacts of climate change are primarily determined by the direction and severity of projected changes in regional precipitation: under the driest climate projection, climate change alone is predicted to reduce Amazonian forest cover by an average of 14%. However, the models predict that CO 2 fertilization will enhance vegetation productivity and alleviate climate-induced increases in plant water stress, and, as a result, sustain high biomass forests, even under the driest climate scenario. Land-use change and climate-driven changes in fire frequency are predicted to cause additional aboveground biomass loss and reductions in forest extent. The relative impact of land use and fire dynamics compared to climate and CO 2 impacts varies considerably, depending on both the climate and land-use scenario, and on the terrestrial biosphere model used, highlighting the importance of improved quantitative understanding of all four factors - climate change, CO 2 fertilization effects, fire, and land use - to the fate of the Amazon over the coming century.
  • Authors:
    • Liang, L.
    • Jia, Z.
    • Wang, X.
  • Source: JOURNAL OF SOIL AND WATER CONSERVATION
  • Volume: 69
  • Issue: 5
  • Year: 2014
  • Summary: Field experiments were conducted from 2008 to 2010 in the Weibei Highlands of China to study the effects of straw incorporation on soil moisture, evapotranspiration (ET), and rainfall-use efficiency (RUE) of maize (Zea mays L.) under semiarid conditions in dark loessial soil. The straw application rates were at low straw ([LS] 4.5 t ha(-1)), medium straw ([MS] 9 t ha(-1)), and high straw ([HS] 13.5 t ha(-1)) rates combined with fixed levels of chemical fertilizers compared with only chemical fertilizers. Straw incorporation significantly increased surface soil moisture at the grain filling stage of maize and significantly improved RUE in the whole growth period of maize. Evapotransipiration at the ten leaf collar to tasseling and the grain filling to maturity stages of maize were significantly increased by straw incorporation. However, ET at the tasseling to grain filling stage of maize was significantly reduced by straw incorporation. Medium straw and HS treatments significantly improved surface soil moisture at the tasseling stage of maize and RUE at the five leaf collar to maturity stage of maize. Increasing straw application rates significantly reduced ET at the grain filling to maturity stage of maize. With increasing experimental years, LS treatment significantly improved surface soil moisture at the five leaf collar to tasseling stage of maize and RUE at the five and ten leaf collar stage of maize, MS treatment significantly increased surface soil moisture at the five and ten leaf collar stages of maize, and HS treatment significantly reduced ET at the sowing to five leaf collar stage of maize. We conclude that a reasonable combination application of straw and chemical fertilizers could make full use of surface soil moisture, inhibit soil evaporation, reduce the ineffective evaporation of crop, and increase RUE at a different growth period of maize and grain yield. In this experiment, the optimum straw application rate for improving RUE and grain yield was MS treatment.
  • Authors:
    • Ganeshamurthy, A. N.
    • Ghosh, P. K.
    • Venkatesh, M. S.
    • Hazra, K. K.
    • Kumar, N.
    • Nadarajan, N.
    • Singh, A. B.
  • Source: Nutrient Cycling in Agroecosystems
  • Volume: 100
  • Issue: 1
  • Year: 2014
  • Summary: Given inherent qualities like N-fixation, P-solublization and nutrient recycling pulses remain the most preferred option for diversification of cereal-based rotations. A long-term experiment was used to assess the effect of including pulses in rice-wheat rotation on soil-plant nutrient dynamics under inorganic and organic nutrient management. Results revealed that pulses were equally responsive to organic and inorganic nutrient management while, growth of cereals especially wheat was restricted severely under organic production system due to low nutrient input. The annual input (kg ha(-1)) of N (103.6-160.8) and P (25.9-34.7) under organic treatment was almost A1/2 of the recommended inorganic rate, while organics supplied higher K and S. Under organic management, the apparent balance of all the nutrients was negative whereas, inorganic fertilization resulted in positive balance of N, P and Zn. Long-term inclusion of pulses in rice-wheat rotation significantly increased soil organic C and available nutrients thus, increased the nutrient uptake by cereals. Mungbean inclusion in rice-wheat rotation significantly (P a parts per thousand currency sign 0.05) increased uptake of N (23.0 %), P (32.9 %) and K (21.1 %) by rice crop. Continuous inorganic fertilization enriched soil available N, P, Zn and B. While organic management maintained higher SOC, available K and S over inorganic treatment. Thus, the study suggested that under organic management N and P nutrition is limiting factor for cereals and needs inorganic supplementation. The study also indicates the need for including pulses in conventional rice-wheat system for optimum nutrient acquisition and long-term soil health management.
  • Authors:
    • Bonsch, M.
    • Dietrich, J. P.
    • Popp, A.
    • Lotze-Campen, H.
    • Krause, M.
  • Source: Land Use Policy
  • Volume: 30
  • Issue: 1
  • Year: 2013
  • Summary: Conservation of undisturbed natural forests, which are important for biodiversity, carbon storage, and other ecosystem services, affects agricultural production and cropland expansion. We analyze the economic impacts of undisturbed natural forest conservation programs on agriculture and the magnitude of avoided deforestation and avoided carbon emissions in the tropics. We apply a global agricultural land use model to estimate changes in agricultural production costs for the period 2015-2055. Our forest conservation scenarios reflect two different policy goals: either maximize forest carbon storage or minimize impacts on agricultural production. In all the scenarios, the economic impacts on agriculture are relatively low. Production costs would increase due to forest conservation by a maximum of 4%, predominantly driven by increased investments in agricultural productivity increase. We also show regional differences in Latin America, Sub-Saharan Africa, and Southeast Asia, due to different growth rates in food demand, land availability and crop productivity. The area of avoided deforestation does not exceed 1.5 million ha yr(-1) in the period 2015-2055, while avoided carbon emissions reach a maximum of 1.9 Gt CO2 per year. According to our results on the potential changes in agricultural production costs, undisturbed natural forest conservation appears to be a low-cost option for greenhouse gas emission reduction. (C) 2012 Elsevier Ltd. All rights reserved.
  • Authors:
    • Moreira, M. A.
    • Nunes, J. C. S.
    • Fontes, P. C. R.
  • Source: Bioscience Journal
  • Volume: 28
  • Issue: 3
  • Year: 2012
  • Summary: Two independent experiments were established in a Red Yellow Argisol Cambic soil objecting to evaluate potato yield and tuber size distribution profile in response to interplant spacing and fertilizer recommendation criteria. One experiment was sprinkler irrigated and the other one was drip-irrigated. Six treatments resulting from the combination of three interplant spacing (29, 36, and 50 cm) and two fertilizer recommendation criteria (by area or by plant number in the area) were evaluated in a completely randomized block design and five replications. In both experiments, marketable potato yield (tuber number and mass) exponentially decreased with the increase in row spacing and it was affected by recommendation criteria. The combination of fertilizer recommendation by area with narrower space optimizes marketable tuber yield by increasing medium and small tubers and also increases fertilizer use efficiency. Environmental, economic and practical implications of the results to potato production are discussed.
  • Authors:
    • Lopes, S. A.
    • Bassanezi, R. B.
    • Gasparoto, M. C. G.
    • Coletta-Filho, H. D.
    • Amorim, L.
    • Lourenço, S. A.
  • Source: Plant Pathology
  • Volume: 61
  • Issue: 4
  • Year: 2012
  • Summary: The objectives of this work were (i) to determine the influence of temperature on infection of citrus by 'Candidatus Liberibacter asiaticus' and 'Candidatus Liberibacter americanus', the two bacterial species associated with citrus huanglongbing (HLB) in Brazil, and (ii) to determine the influence of temperature on citrus colonization by 'Ca. L. asiaticus', which has taken over from 'Ca. L. americanus' as the predominant species in Brazil since 2008. Two experiments were carried out with graft-inoculated Valencia oranges on Rangpur lime rootstocks. Immediately after inoculation the plants were maintained for 423 days in growth chambers under the following night/day temperature conditions: 17/22, 22/27 or 27/32°C, with a dark/light photoperiod of 8/16 h. Infection and colonization of plants were determined using quantitative PCR (qPCR). ' Candidatus Liberibacter americanus' did not infect the plants maintained at 27/32°C; however, infection by 'Ca. L. asiaticus' occurred at all studied temperatures. Two months after inoculation, 'Ca. L. asiaticus' was distributed throughout the inoculated plants, with mean Ct values in the range of 30-31 for leaves and 25-28 for roots. Over time, ' Ca. L. asiaticus' reached the highest titres in mature leaves (mean Ct value=26.7) of citrus plants maintained at 22/27°C. 'Candidatus Liberibacter asiaticus' colonization of citrus plants was negatively affected by the daily temperature regime of 27/32°C (mean Ct value in mature leaves=33.6).
  • Authors:
    • Hau, B.
    • Lourenco, S. A.
    • Stuchi, E. S.
    • Goncalves, F. P.
    • Amorim, L.
  • Source: Plant Pathology
  • Volume: 91
  • Issue: 11
  • Year: 2012
  • Summary: Citrus Variegated Chlorosis (CVC) is currently present in approximately 40% of citrus plants in Brazil and causes an annual loss of around 120 million US dollars to the Brazilian citrus industry. Despite the fact that CVC has been present in Brazil for over 20 years, a relationship between disease intensity and yield loss has not been established. In order to achieve this, an experiment was carried out in a randomized block design in a 3*2 factorial scheme with 10-year-old Natal sweet orange. The following treatments were applied: irrigation with 0, 50 or 100% of the evapotranspiration of the crop, combined with natural infection or artificial inoculation with Xylella fastidiosa, the causal agent of CVC. The experiment was evaluated during three seasons. A negative exponential model was fitted to the relationships between yield versus CVC severity and yield versus Area Under Disease Progress Curve (AUDPC). In addition, the relationship between yield versus CVC severity and canopy volume was fitted by a multivariate exponential model. The use of the AUDPC variable showed practical limitations when compared with the variable CVC severity. The parameter values in the relationship of yield-CVC severity were similar for all treatments unlike in the multivariate model. Consequently, the yield-CVC intensity relationship (with 432 data points) could be described by one single model: y=114.07 exp(-0.017 x), where y is yield (symptomless fruit weight in kg) and x is disease severity ( R2=0.45; P
  • Authors:
    • Hossain, S.
    • Miah, M. A. M.
    • Haque, M. A.
    • Rahman, M. M.
  • Source: Bangladesh Journal of Agricultural Research
  • Volume: 37
  • Issue: 1
  • Year: 2012
  • Summary: Potato is one of the important food crops in Bangladesh. Its demand is increasing day by day. The Tuber Crop Research Centre (TCRC) of BARI released 40 HYV potato varieties and disseminated them in the farmer's fields through different agencies. But most varieties were not adopted well by the farmers due to unknown reasons. Therefore, an attempt was made to assess the level of adoption and profitability of BARI released potato variety at farm level. Data were collected from 150 randomly selected potato farmers from Munshigonj, Bogra and Comilla districts during January-February 2010. The results indicated that 48% potato areas were covered by Diamant variety, 16% by Cardinal, 22% by Granola, and the rest 14% areas were covered by Binella, Asterix, Provento, Felsina, Multa and Hira. The cost of BARI released potato cultivation was Tk 2, 10,629 and Tk 1, 84,135 per hectare on full cost and variable cost basis. The major share of total cost was for seed (42%) followed by fertilizer (21%) and human labour (14%). The average yield of potato was 26 t/ha with gross margin of Tk 1, 51,003 per hectare. The net return of potato cultivation was Tk 1, 24,509 per hectare. The benefit cost ratios were 1.59 and 1.82 on full cost and variable cost basis. Human labour, land preparation, seed, and irrigation had positive and significant effect on potato production. Nonavailability of HYV seed at proper time, lack of technical knowledge, high price of seed and fertilizer, infestation of insect and diseases, and lack of storage facilities were the major problems of potato production.
  • Authors:
    • Abraham, S.
    • Babar, S.
    • Singh, J.
    • Majumdar, G.
    • Venugopalan, M. V.
  • Source: Better Crops with Plant Food
  • Volume: 96
  • Issue: 2
  • Year: 2012
  • Summary: Despite large tracts of irrigated cotton, rainfed systems remain the most important option for improving cotton production in India. Within rainfed fields, the potential effects of adopting high plant population with adequate NPK fertilizer management offer a good opportunity to increase crop productivity.
  • Authors:
    • Naidu, M. V. S.
    • Kailaimannan, R.
    • Venkaiah, K.
  • Source: Madras Agricultural Journal
  • Volume: 99
  • Issue: 4/6
  • Year: 2012
  • Summary: Some important physico-chemical parameters of irrigation water of guava orchards in Prakasam district were evaluated for the criteria of the irrigation water quality. Thirty water samples were collected from three different mandals of the Prakasam district. The present study revealed that pH was neutral to moderately alkaline, Electrical Conductivity (EC) was high, Sodium Adsorption Ratio (SAR) was low to medium and Residual Sodium Carbonate (RSC) was good to marginal. So, initiative must be taken to reduce salt accumulation in the soil through drainage and adopting the highly salt tolerant crops like cotton, mustard and tamarind for the better utilization of the land.