The policy planners are emphasizing to increase the water use efficiency. However, I understand a minimum leaching fraction is essential even for canal water irrigation under arid climates. Arid regions are already facing shortage of good quality water, to meet this shortage poor quality irrigation waters are in use everywhere. I fear, unless magnitude of LR is not considered and met, there must be problems of soil salinity followed by sodicity that is even more difficult to reclaim and manage for crop production for food security.
Dear Ghafoor,
I think I share your concerns and also recognize that the magnitude of improving water use efficiency is context specific. Standards for semi-arid and other eco-regions can not be the same . Just high rate of evaporative depletion of water in arid and semi arid environment can brings down the water use efficiency/water productivity value. But by considering LR you may minimize an irrecoverable damage to your system: means a kind of trade off situation. I am wondering also if LR is computed into water use efficiency calculation? Thanks
Dear Dr Abdul Ghafoor, Yes it is always better to consider LR, but as far as water use efficiency concerned it also pays a lot. I am not agree with your comment that sodicity is more difficult to reclaim. In my opinion salinity is difficult to remove as where ever we through the leachate (drainage effluents) it will create new areas of salinity where as alkali lands can be reclaimed instantly by adding amendments like gypsum, pyrite etc.. Thanks
Dear Sarwan to ameliorate the only salinity, there is no need of any amendment like gypsum etc but are essential for sodic soil conditions. Regarding the disposal of drainage surplus put on other soil seems a bit illogical since in-situ vertical leaching after gypsum application is practiced and collection of that large volume of leachate is impossible. However, in pot studies that your idea seems valid. Also for the disposal of city and industry raw waste water onto soils, could create salinity.
To save water in agriculture just to practice intercropping. In Sudano-Sahelian zone, the Water Use Efficiency Equivalent Ratio is 2 for a 1.2 Land Equivalent Ratio grain (millet, cowpea) rainfed for 6 years with a very high water deficit in Senegal. In Niger, sorghum, rainfed groundnut Association is 1.73 rainfed and irrigated 2.72. The Chinese are beginning to introduce intercropping in irrigated areas.
In the saharan oasian regions of North africa, agriculture have always followed the rule of three levels within the same area, i.e.palm trees, adapted orchard and vegetables...this to ensure the maximum of efficiency and to minimize the evaporation thanks to the palm trees protection. The decrease of waters and the lack of control among the end users created sommes problems of soil salinisation and abandon of some parcels...the idea is to involve the actors for an ideal approach of sustainability taking into account the local caracteristics at all the levels social, land and water characteristics.
Yes Hamed. in the all regions in the world oasian. The soil salinization is a great problem which is less developed in intercropping, because it uses less irrigation water. So the risk of rising salt is less important. And further, tree and shrub planting windbreak reduces evapotranspiration.
I absolutely agree that considering non-consumptive beneficial water use, including leaching, is critical. That said, there is a demonstrably wide range of crop water productivity (based on transpiration, not water application) in regions with similar climates, and increasing yield in those places is one effective way to increase water productivity. I evaluated global trends in water productivity in the attached study.
Article Improvements in crop water productivity increase water susta...
Irrigation is an aberration in Africa. We must prefer the use of RunOn with half-moon, Zai, filter stone bunds, filtering hedges with organic material spreading. and obviously intercropping.
Yes Serge, but this needs a lot of training, infrastructure ans dedicated skills to ensure sustainability...meanwhile, we have to make the end users aware of the risks either at the level of quantity or quality degradation and to arm them with simple and efficient methods to optimize their behaviour and water-use-reflex...so to protect what is remaining of the meager resources for the next générations...
use modern irrigation system is first step, also, cover soil surface by polyethylene mulch, save about 20 % of water for plants, adding organic compost for soil is the third option because compost has high water holding capacity and then save water
Thanks dear colleagues for your contributions. Still I think there is need to further look into future of the water and soil resources sustainability with different options of their use-methodology. For this matter let the discussion continue.
Unless we want to use extra water through inefficiency for leaching along with proper amendments why should one water water through inefficiency
Yes LR is a must otherwise we will increase water use efficiency in the short run and will loos it on the long run. this is because biomass production will be reduced on the long run because of accumulated salts. Therefore, I agree with all the colleagues who suggested inter-cropping systems to increase water use efficiency. May be integrating also some growing systems such as soilless cultures with field production system (by using the drain of soilless culture), will increase the efficiency of using both water and nutrients.
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