• Authors:
    • Balakrishna, A.
  • Source: Journal of Development and Agricultural Economics
  • Volume: 4
  • Issue: 5
  • Year: 2012
  • Summary: Since the introduction of Bt cotton in India, there has been a serious debate going on its impact on cost, returns and productivity. Andhra Pradesh continue to be the largest cultivator of Bt cotton in India and it occupies third position among Indian cotton growing states both in terms of area as well as outturn. In this context, it would be appropriate to analyze the output and efficiency of inputs used in cotton cultivation in Andhra Pradesh state of India. The study is based on a sample survey of selected farmer households in cotton cultivating villages in Andhra Pradesh of India. The study used Multi-stage stratified random sampling method to select the respondents from among the farm households. A detailed structured questionnaire was used to conduct face-to-face interviews with the farmer households. The sample households among the cotton cultivating households who have cultivated non-Bt cotton during last year or last two years have been taken up to study the impact of the presence of technology. In order to ensure the accuracy of the data related to the previous year, care is taken in selection of farm households, those households who have maintained records. The data on input and output variables like cost of seed, cost of labor, cost of irrigation, cost of fertilizers, cost of pesticides and capital used for the both years were collected for the study. To overcome the conceptual problems in quantifying the impact of technology at two points of time, the value of inputs used and output produced was estimated at constant prices based on survey year's price. Also, it is considered the two periods used for the comparison are normal in terms of agro-climatic variables. The Cobb-Douglas production and decomposition analysis techniques were used to estimate the influence of factors and Bt technology on output change. The results of the estimated production functions reveal that seeds and fertilizer is the most important input to which output is highly responsive in both Bt and non-Bt cotton crop situations. The output elasticity of pesticide is higher in non-Bt cotton cultivation than that in Bt cotton cultivation. The decomposition revealed that the net impact of Bt technology alone is estimated to have increased the output by 10.88%. The adoption of Bt technology enabled the farmers to save inputs significantly. And the value of extra output produced per acre with adoption of Bt technology.
  • Authors:
    • Intrigliolo, D.
    • Castel, J.
    • Ballester, C.
    • Castel, J.
    • Testi, L.
  • Source: Acta Horticulturae
  • Issue: 951
  • Year: 2012
  • Summary: Transpiration of well watered (C) and regulated deficit irrigated (RDI) trees was determined by means of the compensation heat pulse method during 2009 and 2010 in commercial citrus groves of 'Clementina de Nules' (CN) and 'Navel Lane Late' (NLL). In both species, sap flow (SF) was measured in two trees per treatment instrumented with two gauges per tree. CN trees were equipped with two different types of gauges (type1 shorter than type2) determining heat velocity from crossing time at four different xylem depths according to Green et al. (2003). In NLL oranges, all the gauges were identical and the data were processed according to the compensation heat pulse+calibrated average gradient (CAG) method (Testi and Villalobos, 2009). Plant water status was determined by midday stem water potential measurements (Psistem). Results showed that the absolute SF values, and especially those from type2 gauges in CN, clearly underestimated tree water use. Tree to tree variability registered in CN (CV=0.09) was lower than in NLL (CV=0.17) which also showed a 17% of within tree variability. The average nocturnal-to-diurnal sap flow ratio was between 7% and 13%. The evolution of relative SF (e.g. SF RDI/SF C) was in agreement with differences in Psistem (r 2=0.78 in CN and 0.84 in NLL). This SF ratio showed the expected decreasing trend during the water restriction period and the recovery when irrigation was reestablished to normal dose. Overall, the results show that sap flow sensors can detect plant water stress but they also highlight some of the problems for accurately measuring transpiration.
  • Authors:
    • Aragues, R.
    • Isidoro, D.
    • Barros, R.
  • Source: Agriculture, Ecosystems & Environment
  • Volume: 155
  • Year: 2012
  • Summary: Nitrogen (N) pollution induced by irrigated agriculture is a significant environmental problem. The main N inputs and outputs were measured or estimated in the semi-arid La Violada irrigation district (Spain). Data on two periods (1995-1998 and 2006-2008) were compared and related to observed changes during the decade in cropping patterns and N fertilization and irrigation management. N fertilization exceeded crop N uptake due to over-fertilization of corn (426 kg N/ha in 1995-1998 and 332 kg N/ha in 2006-2008) and alfalfa (62 kg N/ha). Between the two periods, N fertilization decreased by 56%, primarily due to a change from corn to alfalfa and barley. Accordingly, N losses in the irrigation return flows (IRF) diminished from 31% of the applied fertilizer in 1995-1998 to 20% in 2006-2008. NO 3- concentrations and NO 3-N loads in the IRF decreased from 40 mg/L and 106 kg N/ha in 1995-1998 to 21 mg/L and 22 kg N/ha in 2006-2008, due to lower N fertilization, lower corn area and improved irrigation efficiency. N contamination in the IRF will be minimized by increasing the irrigation efficiency and decreasing the corn area and its N fertilization rates, particularly when supplemental organic N is applied at pre-sowing.
  • Authors:
    • Salakinakoppa, S.
    • Basavanneppa, M.
    • Biradar, D.
  • Source: Journal of Cotton Research and Development
  • Volume: 26
  • Issue: 1
  • Year: 2012
  • Summary: A field experiment was carried out during kharif 2006-2007, 2007-2008 and 2008-2009 at Agricultural Research Station, Siruguppa to study the response of Bt cotton to spacing and fertilizer levels under irrigated ecosystem. The results revealed that among the spacings, closer spacing of 90*45 cm produced significantly superior seed cotton yield (2243 kg/ha) over wider spacing of 90*90 cm (1867 kg/ha) and it was at par with 90*60 cm (2121 kg/ha). Among the fertilizer levels, application of 125 per cent NPK registered higher seed cotton yield over 75 per cent NPK but at par with application of 100 per cent NPK. On the contrary the ancillary data indicated that, higher seed cotton yield/plant (136.11 g/pl) and more bolls (40.46/pl) were observed in wider row spacing of 90*90 cm as compared to other spacings. In case of fertilizer levels more seed cotton yield/plant was observed in application of 125 per cent NPK (130.40 g/pl) as compared to 75 and 100 per cent fertilizer levels. Similar trend in bolls/plant, sympodia and boll weight were found as that of yield. Further, higher gross return (Rs.56774/ha), net returns (Rs.30837/ha) and B:C ratio (2.20) was recorded in closer spacing of 90*45 cm as compared to 90*90 cm. Among the fertilizer levels, application of 125 per cent RDF recorded maximum gross return (Rs.55256/ha), net returns (Rs.29415/ha) and B:C Ratio (2.15) which was significantly superior to 75 per cent NPK but at par with 100 per cent NPK. From the results, it can be concluded that, Bt cotton responds to closer spacing of 90*45 cm with the application of 100 per cent NPK for realizing higher yield and monetary advantages.
  • Authors:
    • Wery, J.
    • Blanco, M.
    • Belhouchette, H.
    • Flichman, G.
  • Source: Computers and Electronics in Agriculture
  • Volume: 86
  • Year: 2012
  • Summary: The aim of this study was to evaluate the sustainability of farm irrigation systems in the Cebalat district in northern Tunisia. It addressed the challenging topic of sustainable agriculture through a bio-economic approach linking a biophysical model to an economic optimisation model. A crop growth simulation model (CropSyst) was used to build a database to determine the relationships between agricultural practices, crop yields and environmental effects (salt accumulation in soil and leaching of nitrates) in a context of high climatic variability. The database was then fed into a recursive stochastic model set for a 10-year plan that allowed analysing the effects of cropping patterns on farm income, salt accumulation and nitrate leaching. We assumed that the long-term sustainability of soil productivity might be in conflict with farm profitability in the short-term. Assuming a discount rate of 10% (for the base scenario), the model closely reproduced the current system and allowed to predict the degradation of soil quality due to long-term salt accumulation. The results showed that there was more accumulation of salt in the soil for the base scenario than for the alternative scenario (discount rate of 0%). This result was induced by applying a higher quantity of water per hectare for the alternative as compared to a base scenario. The results also showed that nitrogen leaching is very low for the two discount rates and all climate scenarios. In conclusion, the results show that the difference in farm income between the alternative and base scenarios increases over time to attain 45% after 10 years.
  • Authors:
    • dos Santos, C.
    • Sofiatti, V.
    • Bezerra, J.
    • da Silva, B.
    • Bezerra, B.
  • Source: Agricultural Water Management
  • Volume: 107
  • Year: 2012
  • Summary: During the twentieth century, the cotton crop was the main agricultural product in the semiarid regions of Brazil, with over 3.2 million hectares planted. However, due to structural problems, this activity became uncompetitive and economically unfeasible, being virtually wiped out in the eighties. The revival of cotton growing in semiarid lands of Brazil is important to the regional economy. However, the adoptions of new technologies mainly related to the water use efficiency are needed. Thus, accurate ETc estimates are required for efficient irrigation management. The K-c method is a practical and reliable technique for estimating ETc, and has been vastly applied by the farmers in the semiarid lands of Brazil. However, the use of K-c values listed in FAO-56 can contribute to ETc estimates that are substantially different from actual ETc. Hence the importance of determining K-c values experimentally. A field study on sprinkler-irrigated cotton was carried out during the dry seasons of 2008 and 2009 years in the Apodi Plateau, Brazilian semiarid lands. This study aims to determine ETc and the K-c curve values using the Bowen Ratio Energy Balance (BREB) technique. The locally developed K-c curves are compared with generalized FAO K-c values adjusted for local climate and management. The ETc values were 716 mm and 754 mm in 2008 and 2009, respectively. These values were higher than those observed in other areas of Brazilian semiarid. These differences are attributed to weather heterogeneity in the region. The average of K-c values were 0.75, 1.09 and 0.80 for initial, middle and end, of growing season, respectively. These values were lower than the Kc-FAO-Adjusted to local conditions. For this reason, ETc values obtained from Kc-FAO-Adjusted were overestimated by 12% in both the years. The irrigation scheduling based on the Kc-FAO-Adjusted increases production cost and yield loss. (C) 2012 Elsevier B.V. All rights reserved.
  • Authors:
    • Mustian, J.
    • Bordovsky, J.
  • Source: Applied Engineering in Agriculture
  • Volume: 28
  • Issue: 3
  • Year: 2012
  • Summary: The recent increase in the use of subsurface drip irrigation (SDI) for cotton production in the Texas High Plains has resulted in questions concerning drip lateral position and orientation relative to crop rows. Field experiments were conducted at Halfway, Texas to evaluate traditional SDI installations with crop rows spaced at 0.76 and 1.02 m; crop row to lateral offsets of 0.0, 0.13, 0.25, and 0.38 m; and crop rows perpendicularly crossing SDI laterals spaced at 0.76, 1.02, and 1.52 m. Traditionally installed SDI with cotton rows spaced at 0.76 m resulted in generally higher yield than those spaced at 1.02 in; however, differences were not significant over the 5-year period. Yields were significantly different between individual rows of adjacent row pairs irrigated with single SDI laterals when row offsets were greater than 0.25 m on 0.76-m row spacing. However, cotton plants from rows closest to the SDI lateral largely compensated for yield losses of rows farthest from the lateral. When considering perpendicularly crossing 1.52-m spaced laterals with 0.76-m wide crop rows, only modest declines in cotton lint yield (1.5% and 3.3%) occurred compared to traditional parallel row-lateral orientation with the same lateral and row spacing. With crop rows perpendicular to laterals, SDI lateral spacings resulted in average yields of 1802, 1869, and 1903 kg ha(-1) at distances of 1.52, 1.02, and 0.76 m, respectively. Orienting rows perpendicular to drip laterals using 0.76-m crop row widths resulted in significantly higher yields and irrigation water use efficiencies than 1.02-m row widths at high irrigation capacity. As water availability declines, these results will provide producers additional information on SDI installation and management.
  • Authors:
    • Villalobos, F.
    • Gomez-Macpherson, H.
    • Boulal, H.
  • Source: Field Crops Research
  • Volume: 130
  • Year: 2012
  • Summary: In the Mediterranean region, conservation agriculture principles like minimum soil disturbance or retaining residues on soil surface are rarely applied in irrigated annual cropping systems. This paper compares a conservation agriculture practice, permanent bed planting (PB), with a conventional system in which the ridges are reformed annually (CB). Comparisons were made throughout a crop sequence of cotton (Gossypium hirsutum L)-maize (Zea mays L) - cotton in which PB was introduced before the maize cropping. Traffic was controlled during the study. Both maize and cotton crops produced higher leaf area index and biomass under PB than CB and Sand 24% higher yield respectively though the yield benefit for maize was not significant. The PB system did not improve Water-use Efficiency but delayed water use until the later growth stages. Soil organic matter (SUM) was significantly higher in PB compared to CB one year after the introduction of the system, and this difference was due to higher SUM in the 0-0.05 m layer, particularly in the furrows. The lack of negative effects of PB on yield and the positive effects on SUM, coupled with increased water infiltration and reduced erosion shown in previous studies, point to the beneficial adoption of PB in the region assuming the patterns are confirmed in the longer term. (C) 2012 Elsevier B.V. All rights reserved.
  • Authors:
    • Barnes, E.
    • Scharf, P.
    • Taylor, R.
    • Brown, C.
    • Wheeler, T.
    • Bronson, K.
  • Source: Soil Science Society of America Journal
  • Volume: 76
  • Issue: 3
  • Year: 2012
  • Summary: Nitrogen is the main nutrient limiting irrigated cotton (Gossypium hirsutum L.) production in the southwestern United States. Canopy spectral reflectance may assess the need for in-season N in irrigated cotton and guide N fertilizer applications. However, calibration of remote sensing indices such as normalized difference vegetative index (NDVI) to the crop's need for N fertilizer is difficult. Well-fertilized reference strips or plots reference NDVI data in the crop area of interest but can result in rank growth and reduced lint yields. Recently, Oklahoma State University developed a calibration procedure of using multiple, sequential, N rate calibration plots, or a ramp approach for wheat (Triticum aestivum L) and corn (Zea mays L.). We tested this approach in irrigated cotton fields in Lubbock County, Texas, in 2008 and 2009. The main objective of this research was to test a calibration ramp approach to determining optimum in-season N fertilizer rates in irrigated cotton in West Texas. Near infrared, red, and amber reflectance was measured with active spectroradiometers at 1 m above the canopy. Wide ranges in soil type and irrigation amounts influenced NDVI much more than N fertilizer rate. Normalized difference vegetative index at mid-bloom and at peak bloom were positively related to N fertilizer rate in only one ramp in each year. These two ramp-years also had significant N fertilizer rate response in lint yield. Ramps that did not have mid- or peak bloom NDVI responses to N rate, likewise had no lint yield response to N rate. In both low irrigation- low N input and in high irrigation-high N input farms, in-season NDVI correctly predicted lint yield response to N fertilizer rate.
  • Authors:
    • Gitz, D.
    • Booker, J.
    • Bednarz, C.
    • Lascano, R.
    • Bufon, V.
  • Source: Irrigation Science
  • Volume: 30
  • Issue: 4
  • Year: 2012
  • Summary: Crop irrigation with subsurface drip (SDI) is increasing in the semiarid Texas High Plains (THP). Information on drip-tubing positioning, irrigation strategies, and wetted soil area is needed to increase rainwater effectiveness when well capacities are inadequate to meet full irrigation requirements. Time and resources necessary to test SDI strategies for different conditions through field experimentation is too large. However, a mechanistic model such as Hydrus-2D can quantify the effect of different installation geometries and irrigation strategies. Our objective was to experimentally validate the Hydrus-2D in an Amarillo soil in THP so that the model can be used to evaluate different irrigation frequency and timing strategies for SDI cotton. Results showed that Hydrus-2D simulated volumetric soil water content within +/- 3% of measured values, and simulation bias represented the smaller portion of the simulation error, indicating that the model can be used to evaluate irrigation strategies.