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Agri Overview

Saline agriculture and reclamation approach           Home
By Ghulam Hassan

About 2.67 million hectares in Punjab is under salinity/sodicity menace at varying degrees. The problem is on the rise due to prolonged drought and diminishing canal supplies.

Saline agriculture and reclamation approach Fresh water supplies are decreasing with increasing demand for drinking, industry and agriculture.

Under prevailing circumstances it is not advisable to reclaim sodic or saline sodic soils with gypsum as an acre foot of quality water is required to leach down the salts generated by each ton of gypsum. Failing leaching process such soils will be converted into saline.

Planting of salt tolerant forest or horticultural plants or salt tolerant crop varieties is known as saline agriculture. Forest especially Acacia, Prosopis, and Eucalyptus etc., are highly tolerant to salinity but relatively prone to sodicity.

Horticultural plants like dates, guava, pomegranate, falsa etc., also tolerate salinity to varying extent. It is low in arable crops. Thus, tolerance to salinity by plant is not absolute but relative. On the other hand in the field, salinity/sodicity varies to a large extent therefore establishment of uniform or satisfactory crop stand by usual farming practices is not obtained and poor harvest or total failure results.

Soil Salinity Research Institute, Pindi Bhattian has devised some practices, whereby the success of crops and trees increases to a great extent in salt affected soils.

It is well documented that successful cultivation of plants removes salts from the soil and ultimately normal agriculture is restored on such land. Since the Institute is located in rice zone, the research was done on rice-wheat rotation and forest and fruit trees. Soil analysis is a prerequisite.

In rice cultivation, the steps are enlisted are: raise a nursery of tolerant species in salt free soil; if the ECe of the field exceeds 8 dSm-1, flood the field for at least a week after deep ploughing (if possible) otherwise plough the field with cultivator; avoid puddling; number of seedlings per hill should be increased to gypsum requirement plus two; follow the usual irrigation, fertilizer and plat protection measures. Returning of rice straw to soil will hasten the reclamation process.

Germination of wheat seed if sown at field capacity is reduced if ECe of field exceeds eight, however, tolerant varieties can sustain somewhat higher salinity. In soils having ECe more than 10 dSm-1, the sowing method will be to prepare the field by cultivation and planking; flood the field and broadcast seed or broadcast seed and flood the field; or drill the seed and irrigate the field; good crop stand can be established in saline sodic soil provided its gypsum requirement is below three tons per acre; But the first irrigation should be delayed to 35 days and it should be light; if gypsum requirement of a saline sodic field is up to five tons per acre, ridge sowing is better; on well prepared dry land broadcast seed and fertilizer (phosphorus source should be SSP) and make ridges with ridger and then irrigate so that crowns are not submerged. It should fill the furrows between ridges.

Tree plantation: Ultra salt affected soils can be used for growing of forest or fruit trees like date palm, guava, ber, jamin etc. If ECe is >30 dSm-1 Acacia Spp. should be preferred; keeping in view the recommended row to row distance, make ditches at least one foot deep; dig pits three feet in diameter and three feet deep at recommended plant to plant distance; if compact layer is encountered at this depth, make further three feet deep auger hole in centre of the pit which will facilitate root penetration up to six feet; fill the pits with silt and irrigation to settle the silt; transplant tree sapling in centre of the pit.

The advantages of it are that it will save precious input i.e., water and the cost of amendments and their application; ensure income to the owners of salt affected lands; facilitate salt transportation rather than their cycling in the profile; improve the economy of the country.

Courtesy: The DAWN

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