09-08-2012, 12:20 PM
Leaching
Leaching.ppt (Size: 70 KB / Downloads: 37)
In this process, the land is flooded with adequate depth of water. The alkali salts present in the soil, get dissolved in this water, which percolate down to join the water table or drained away by surface and sub- surface drains. The process is repeated till the salts in the top of the land are reduced to such as extent that some salt resistant crop can be grown. This process is known as leaching.
LEACHING REQUIRMETS
In order to maintain status quo on the salinity of a given soil, and to avoid any further increase in its salinity, it is necessary to apply water to the soil in excess of consumptive uses (i.e. the requirement to meet the evapo transpiration needs).
This excess water will flow down beyond the root zone of the crop to the underground drainage system or to the underground reservoir, washing down the excess salts, which otherwise would have been deposited in the soil to further increase the salinity of the soil.
This excess water, which is required to meet the leaching needs, is generally expressed as the percentage of the total irrigation water applied to the soil to meet the consumptive use as well as the leaching needs.
NITROGEN
Nutrient that requires better management.
Adequate water management is required for efficient use of nitrogen.
Nitrate leaching is influenced by irrigation systems, soil characteristics, climatic condition.
CONCLUSION
Irrigation applied at optimum rates and times for
plant growth can enhance N uptake and reduce
nitrate leaching losses
Spray irrigation systems have a lower nitrate
leaching loss cf. older flood irrigation systems
New soil moisture measurement technologies and
irrigation scheduling can increase efficiency of
water use and reduce the risk of leaching