• Authors:
    • Jimenez-Martinez, J.
    • Elorza, F.
    • Candela, L.
    • Igel, W.
  • Source: Computers and Electronics in Agriculture
  • Volume: 86
  • Year: 2012
  • Summary: According to the general circulation models (CGMs) for future climate projections, a temperature increase, precipitation decrease, and an increase in the variability of extreme events may be expected in the future, likely reducing available water resources. For the western Mediterranean, future climate change projections indicate that temperature increase may range from 1.5°C to 3.6°C, and the precipitation decline will reach between 10% and 20%, which may result in a significant reduction of natural groundwater recharge. With the use of modelling tools, the amount of groundwater recharge under different climate change scenarios and varying agricultural management practices can be predicted, and water budget attributes can be estimated, which may allow for quantifying impacts, and assist in defining adaptation strategies. For the Inca-Sa Pobla basin (Balearic Islands, Spain), under future climate change projections, agricultural management alternatives of crop type distribution and irrigation demands are required for planned adaptation strategies. In the area, where irrigation water for agricultural practices originates from groundwater resources, adaptation measures based on a change from mixed crops to potatoes and a 20% decrease of agricultural land cultivation have proven to be efficient for the hydrologic system and associated wetland sustainability.
  • Authors:
    • Carr, M.
  • Source: Experimental Agriculture
  • Volume: 48
  • Issue: 3
  • Year: 2012
  • Summary: The results of research on the water relations and irrigation need of Citrus spp. are collated and reviewed in an attempt to link fundamental studies on crop physiology to drought mitigation and irrigation practices. Background information is given on the centres of origin (south-east Asia) and of production of citrus (areas with subtropical Mediterranean-type climates). The effects of water stress on the development processes of the crop are summarised followed by reviews of the plant water relations, crop water requirements, water productivity and irrigation systems. The topic is complicated by the diversity of species and cultivars (including rootstocks) that are embraced within Citrus spp. The effects of water availability on vegetative growth are understood in general terms, but the relationships have not yet been quantified. Similarly, the need for a 'rest period' to induce flowering is understood, but its magnitude (in terms of a drought stress index or day-degrees) does not appear to have been specified with precision. Again, the effects of drought on flower and fruit formation and retention are understood in general terms, but the relationships have not been quantified in useful ways for specific cultivars. Rooting depth and distribution have only been described in a limited number of situations. Environmental factors influencing stomatal conductances are generally well described and relationships with some growth processes established. Compared with other crops, low stomatal/canopy conductance restricts water use of Citrus spp. Some (limited) progress has been made in quantifying crop water requirements in specific conditions. Despite many recent attempts to specify how little water can be applied at specific growth stages to optimise water productivity through regulated deficit irrigation, no consensus view has emerged. The yield response to 'full' irrigation is of the order 6-7 kg fresh fruit m -3 as a result of an increase in the number of fruit of marketable size. There are also improvements in fruit quality. The most effective way of irrigating a citrus orchard is with a microirrigation system (drip or microsprinklers), but both methods require answers to the question: what proportion of the root zone needs to be irrigated? Both methods, especially drip, allow water to be applied (with fertigation) at very frequent intervals (including several times a day), although formal evidence of the benefits to be obtained from this level of intensification is lacking.
  • Authors:
    • Williams, J.
    • Cetin, M.
    • Ibrikci, H.
    • Lounis, A.
    • Hartani, T.
    • Isidoro, D.
    • Topcu, S.
    • Sellam, F.
    • Barros, R.
    • Cavero, J.
    • Araguees, R.
  • Source: Agricultural Water Management
  • Volume: 103
  • Year: 2012
  • Summary: One of the main constraints of irrigated agriculture is off-site N pollution due to export of nitrate in irrigation return flows (IRF). Models capable of simulating the growth of crops and the N loads in IRF as affected by irrigation and N fertilization may be valuable tools in watershed studies. The Agricultural Policy Environmental eXtender (APEX) model was used to assess best management practices for reducing off-site N loads in the IRF of three Mediterranean irrigated watersheds (Akarsu in Turkey, La Violada in Spain and Sidi Rached in Algeria). The watersheds (ranging from 4013 to 10,971 ha) were monitored along three hydrological years to determine the volume of IRF and the NO3-N concentrations and loads in IRF. APEX was calibrated with the data of the first two years and validated with the last year's data. APEX adequately simulated crop evapotranspiration and the volume of IRF and N loads in the IRF (errors
  • Authors:
    • Chen, X.
    • Zhang, T.
    • Chen, G.
    • Chen, Z.
    • Chen, X.
    • Zhang, T.
    • Chen, G.
    • Chen, Z.
  • Source: Xinjiang Agricultural Sciences
  • Volume: 49
  • Issue: 5
  • Year: 2012
  • Summary: Objective: Study the feasibility of secondary treated waste water for agricultural irrigation in Urumqi. Method: Chinese cabbage and cotton were used as experimental materials and treated respectively with treatment 1 which is control, treatment 2 which is 50% reclaimed water, and treatment 3 which is 100% reclaimed water. POD, CAT, SOD, MDA, and dry weight of Chinese cabbage and production of cotton were detected. Result: Results showed that inhibitory effects of reclaimed water were proportional to the treatment duration and concentration. The dry weight of 50% reclaimed water treated treatment 1, as the order treatment 2 > treatment 1 > treatment 3. Because the nutrients and harmful substances respectively played promotion and inhibition on the growth of Chinese cabbage, treatment 2 growed better; The yields per acre of cotton under three kinds treatments were significant difference, as the order treatment 1 > treatment 2 > treatment 3, that means reclaimed water inhibits the growth of cotton. Conclusion: Reclaimed water showed different effects on different crops. On cabbage, it mainly showed promotive effect, while on cotton, it mainly showed inhibition effect.
  • Authors:
    • Li, Y.
    • Cao, W.
    • Lei, X.
    • Chen, D.
  • Source: Sensor Letters
  • Volume: 10
  • Issue: 1-2
  • Year: 2012
  • Summary: CIDSS, an irrigation decision support system (DSS), was developed to satisfy the need for drip irrigation under plastic film of cotton yield management in Xinjiang, China. It is compartmentalized into four main modules: database management, real-time moisture diagnosis, real-time irrigation decision making, and production management decisions. The present study used the Kriging interpolation method to estimate soil moisture caused by spatial variability. The Least Squares Support Vector Machines (LSSVM) model and an empirical model based on the exponential depletion relation of soil moisture were also employed to predict soil moisture. A cotton production management expert system was realized by embedding C Language Integrated Production System. By integrating the interfaces of the moisture sensor, the automatic meteorological station in the field, and the solenoid valve control system, the present study solved the problem of the data for real-time decision making. Finally, the use of CIDSS was demonstrated through characteristic case studies on cotton areas in Xinjiang Uygur Autonomous Region, China.
  • Authors:
    • Oliveira, P.
    • Coelho Filho, M.
    • Coelho, E.
  • Source: Acta Horticulturae
  • Issue: 928
  • Year: 2012
  • Summary: Meeting the increased water requirement in agriculture due to the increases of irrigated areas in order to provide food for growing populations, relies on the application of water with increased efficiency. This work evaluated the partial root drying technique for lemon 'Tahiti' trees under semi-arid climate conditions in the north of Minas Gerais. The experiment was carried out in randomized block design with nine treatments and four replicates. Treatments were based on percentages of reduction of calculated irrigation water depth, i.e., 25% corresponding to the reduction of irrigation on one quarter of the area occupied by the plant and 50% corresponding to the reduction of irrigation on half of the plant area during three phonological phases (I, II and III) of lemon 'Tahiti'. The results showed that irrigation scheduling using the partial root drying method may be performed with any of the treatments evaluated. The larger yields and water use efficiencies were obtained for treatments T7 and T8 which were a reduction of 25% of total irrigation every 7 or 15 days during flowering followed by a reduction of 50% of total irrigation every 7 or 15 days in phases II and III.
  • Authors:
    • Sutton, B.
    • Neilsen, J.
    • Mahan, J.
    • Burke, J.
    • Conaty, W.
  • Source: Crop Science
  • Volume: 52
  • Issue: 4
  • Year: 2012
  • Summary: A plant-based thermal optimum approach to irrigation scheduling provides potential benefits in that water applications are scheduled on the basis of plant response to water status. Such irrigation systems require a defined thermal optimum for the crop and while such optimum values have been identified for cotton (Gossypium hirsutum L.) cultivars in the United States, there is no information of this type for cultivars common in Australian production. This paper outlines a threefold approach to determining the optimum temperature (T-opt) of the commercial Australian cotton cultivar Sicot 70BRF in an Australian production system. It combines the use of a laboratory-based fluorescence assay, field-based net C assimilation rate (A) and stomatal conductance to water vapor (g(s)), and canopy temperature (T-c)-yield relations. The fluorescence assay showed a T-opt between 28 and 30 degrees C while leaf gas exchange rates peaked at a leaf temperature (T l) of 29 degrees C. The T-c-yield relations peaked at 26 degrees C, with yield reductions observed when T-c > 28 degrees C. We conclude the T-opt of the Australian upland cotton cultivar Sicot 70BRF to be 28 +/- 2 degrees C. This T-opt will provide valuable information for use in thermal optimum irrigation scheduling systems.
  • Authors:
    • Weatherhead, E.
    • Jones, R.
    • Keay, C.
    • Daccache, A.
    • Stalham, M.
    • Knox, J.
  • Source: Journal of Agricultural Science
  • Volume: 150
  • Issue: 2
  • Year: 2012
  • Summary: The viability of commercial potato production is influenced by spatial and temporal variability in soils and agroclimate, and the availability of water resources where supplementary irrigation is required. Soil characteristics and agroclimatic conditions greatly influence the cultivar choice, agronomic husbandry practices and the economics of production. Using the latest (UKCP09) scenarios of climate change for the UK, the present paper describes a methodology using pedo-climatic functions and a geographical information system (GIS) to model and map current and future land suitability for potato production in England and Wales. The outputs identify regions where rainfed production is likely to become limiting and where future irrigated production would be constrained due to shortages in water availability. The results suggest that by the 2050 s, the area of land that is currently well or moderately suited for rainfed production would decline by 88 and 74%, respectively, under the 'most likely' climate projections for the low emissions scenario and by 95 and 86%, respectively, for the high emissions scenario, owing to increased likelihood of dry conditions. In many areas, rainfed production would become increasingly risky. However, with supplementary irrigation, c. 0.85 of the total arable land in central and eastern England would remain suitable for production, although most of this is in catchments where water resources are already over-licensed and/or over-abstracted; the expansion of irrigated cropping is thus likely to be constrained by water availability. The increase in the volume of water required due to the switch from rainfed- to irrigated-potato cropping is likely to be much greater than the incremental increase in water demand solely on irrigated potatoes. The implications of climate change on the potato industry, the adaptation options and responses available, and the uncertainty associated with the land suitability projections, are discussed.
  • Authors:
    • Batista Almeida de Aquino, R.
    • Lima, T.
    • Lima Neves, J.
    • Berger, P.
    • de Aquino, L.
  • Source: Pesquisa Agropecuaria Tropical
  • Volume: 42
  • Issue: 1
  • Year: 2012
  • Summary: PHOSPHORUS SPLIT APPLICATION ON IRRIGATED COTTONMost regions where cotton is cultivated in Brazil present low soil fertility, especially concerning the available phosphorus (P). This study aimed to evaluate the phosphorus split application on irrigated cotton, for reaching a higher phosphate fertilization efficiency, in comparison to the traditional application at sowing. The experiment was conducted in Quartzarenic Neosol with 22 mg dm(-3) of P (medium availability), in the north region of the Minas Gerais State, Brazil. The design used was randomized blocks, in a (4x3) + 3 factorial scheme, with three replications. Treatments consisted of P2O5 doses (0 kg ha(-1), 30 kg ha(-1), 60 kg ha(-1), 120 kg ha(-1), and 180 kg ha(-1)) and three split applications (80% and 20%; 60% and 40%; 40% and 60% of the P dose applied respectively at sowing and at 35 days after emergence (DAE)), plus the application of 0 kg ha(-1), 60 kg ha(-1), and 120 kg ha(-1) of P2O5 at sowing. The P source was the granulated triple superphosphate, and the P content in the shoots increased according to the doses applied. Nutrient contents in the index leaf, except for P, were not influenced by P levels and split applications. The P content in the index leaf and the number of cotton bolls per plant increased with the increment of P doses, but were not affected by the phosphate fertilizer split application. The application of 40% of the P dose at sowing and the remaining amount split at 35 DAE decreased the cotton boll yield, with no significant effect for the other split applications.
  • Authors:
    • da Silva Soares, L.
    • Freire, A.
    • Alves de Oliveira, F.
    • de Medeiros, J.
    • de Oliveira, F.
  • Source: Revista Ciencia Agronomica
  • Volume: 43
  • Issue: 2
  • Year: 2012
  • Summary: This study was conducted to evaluate the effect of different salinity levels of irrigation water and seed treated with growth regulator on the yield of cotton. It was used an entirely statistical randomized design, in a factorial scheme 5 x 2, with four replications. The treatments resulted from the combination of four salinity levels of irrigation water (S-1-0.5; S-2-2.0; S-3-3.5; S-4-5.0 and S-5-6.5 dS m(-1)) in treated and untreated seeds with growth regulator. The variables were: production of cotton, seed and fiber, 100 seed weight and percentage of fiber. There was not interaction between salinity levels and seed treated. The parameters of cotton production are reduced with the use of water salinity from 3.5 dS m(-1), independent of seed treated or not with growth regulators. Agronomic traits 100 seed weight, percentage of fiber and seed cotton production are not influenced by mepiquat chloride. The seed treatment with growth regulator do not affects the adverse effect of salinity.