Research experiments on various aspects of salinity/sodicity, land use and brackish water usage were conducted. Following technologies were formulated on the basis of results obtained from concluded experiments of different nature.
Safe use of brackish tube well water for crop production
Brackish water of medium quality (EC 2 dS/m, SAR 18 and RSC 3 me/l) can successfully be used through cyclic strategy without significant losses in yield and ill effects on soil properties. Brackish and canal water can be used in a cyclic manner; brackish water for rice and canal water for subsequent wheat or brackish water for wheat and canal water for subsequent maize/summer fodders. Keeping in view the very limited and irregular supply of canal water, a short cyclic use strategy has also been devised. Three irrigations of tube well water followed by two canal water irrigations proved also useful.
When the water is highly sodic, it can be used on long term basis by application of gypsum (calculated on the basis of the quality of tube well water) applied into the soil after harvesting of wheat crop. Combination of sesbania green manure with gypsum can prove further useful for the maintenance of physical conditions (Bulk density, porosity and hydraulic conductivity) as well as fertility of soil. Application of farmyard manure @ 10 t/ha also prove useful for the same purpose.
If tube well water is solely available and it is saline as well, it can be used by application of 10 to 25 % more water than the crop requirements (Known as delta of water). The calculation of additional amount will depend upon the quality of water to be used and will be determined after testing of water in the laboratory.
One very easy and important approach (checking and utilization of rainy water) is being ignored. Rainfall water is very precious and highly helpful to leach down accumulated salts during irrigation with tube well water. The boundaries of fields should be kept strong and land should remain ploughed (if no crop is grown) before the on set of monsoon season. No drop of useful rainy water should be lost in the shape of runoff.
Production technology for Shaheen Basmati
The production technology for Shaheen Basmati was standardized through research and zonal trials. This variety can be transplanted from July 5 to August 5 while the best time is, around 20th July. The recommended dose of fertilizer is 120-90-70 kg ha-1. (N, P2O5 and K2O). Seedlings should be transplanted at the distance of 22-cm. from plant to plant and row to row.
Reclamation of barren salt affected lands
Highly salt affected barren soils must be reclaimed before growing of crops. Appropriate technique of reclamation must be adopted that suits prevailing soil, water, and other related conditions. Soil texture, porosity, hydraulic conductivity and drainage are the important soil characteristics while the quality of water is also a basic consideration. Even tube well water can be used for reclamation when canal water is not available. However, the salt content of irrigation water to be used for reclamation must be less than the soil and the tolerance limit of the crops to be grown subsequently. Gypsum application proved the most effective and economical for reclamation but its quality must be ensured and quantity must match requirement of the soil. Mixing of gypsum uniformly and leaching of salts through ponding of water on the surface for about two weeks or four to five deep intermittent deep irrigations are the other key factors in this regard. The other important detail of gypsum technology are as under.
Scrapping of salts from the upper 5 cm layer not only reduces gypsum and subsequent water requirements but also the reclamation process becomes rapid due to less quantity of remaining salts that are to be removed.
Economical fineness of gypsum is 30 meshes.
The quantity must be adjusted according to soil texture that will not only save the expenditure but also decrease water requirement. In case of sandy soils, 50 % of the soil gypsum requirement (SGR) may suffice the purpose while for medium textured soils it can be 75 % of the SGR.
When the soil is heavy in texture, gypsum has not only to be added equal to 100 % SGR but also has to be combined with farm yard manure, compost, rice straw, rice husk, press mud, poultry manure or sesbania (green manure) @ 10 t/ha. This practice also increases soil fertility and productivity. Sometimes, sulphuric acid (50- 100 Kg/acre) is also recommended to tackle the situation so that passage of water becomes possible.
In case of presence of hard layer in the soil profile (especially in the 30 cm surface) deep ploughing/ chiseling is needed for effective leaching of salts.
When the drainage of the soil is restricted, horizontal flushing of applied irrigation water gave the encouraging results instead of leaching.
Gypsum must be spread and mixed uniformly.
Subsequent leaching of salts with irrigation water (as described in the earlier part).
Biological reclamation of slightly and moderately salt affected soils
Such types of soils are often under crops but due to the yield level and income obtained, the cultivation often becomes uneconomical. Application of less quantity of gypsum (25 % SGR) or organic amendments like rice straw, manures or press mud @ 8 t/ha. converts into productive land. Green manuring of legumes/ grasses (Guara, Jantar, Kallar grass, sorghum or Bajra) also indicted equally effective.
Standardization of sowing methods for various crops
Wheat crop can face poor germination and yield losses due to more moisture and less aeration, in the absence of water leaching that result in standing of water on the surface. More often, the germination is very poor and crop stand is either patchy or very less. This problem can successfully be solved by growing wheat on ridges. Similarly rice can be grown successfully by transplanting more number of seedlings per hill (2 to 5 seedlings). The age of nursery should be more than transplanted under normal soil conditions. Rice seedlings of 35-40 days performed better than younger seedlings in salt affected soils.
Restoration of soil physical properties of fine textured saline sodic or sodic soil
The deteriorated physical properties (Bulk density, porosity and hydraulic conductivity) of dense saline sodic or sodic soil severely hinder leaching of salts, resultant reclamation and subsequent crop production because no water can pass through surface layers. These can be altered by addition of sand (40-50 tons /ha) or restored with gypsum application when coupled with farmyard manure, press mud and sesbania green manure (10 t/ha). Use of brackish water instead of canal water also proved useful. This technique not only helped in improvement of physical properties but also the germination and yield of crops in hard impervious salt affected soils.
Growing of two rice and one wheat crop and other appropriate crop sequences in salt affected soils
Coarse rice (NIAB-IRRI-9) and Shaheen Basmati followed by wheat in recently reclaimed soil is the best crop sequence which ensures maximum production of around 14 t.ha-1 cereals in a year (Coarse rice=6.0 t.ha-1 , Basmati rice=4.0 t.ha-1 and wheat=4.0 t.ha-1). Other appropriate crop sequences are: Rice- wheat- sesbania, Rice- wheat, Rice- barley, Rice- Berseem (alfalfa), Rice- oats and Wheat- sorghum. These crop sequences are effective and economical when the soil is moderately salt affected (Soil EC< 6 dS/m and SAR< 30). If the soils are barren and highly salt affected then such soils must be reclaimed by addition of amendments and subsequent leaching so as to bring the salinity parameters within the tolerance range of these crops.
Application of organic materials
Poultry manure, Farm yard manure, sesbania green manure, press mud, , wheat straw and eucalyptus leaves proved useful to increase the rice yield by 50 to 32 % when added @ 20 t/ha in recently reclaimed/ under reclamation soils by using gypsum in the required quantities. Their effectiveness was assessed and the yield ranged from 2.24 to 4.48 t.ha-1.
Use of MOP verses SOP
Sulphate of potash (SOP) has a little edge over Muriate of potash (MOP) in rice- wheat cropping system under canal as well as brackish water of tube-wells.
Response of wheat to Copper and Boron in saline sodic soil
The deficiency of copper for wheat crop was found which could be cured by application of Cu @ 2.5 Kg ha-1. Boron application of 1 Kg ha-1 also proved useful in saline sodic soil.
Improved technology for transplanting of forest/fruit saplings
The effective formulation is making pits 2 feet long, 2 feet wide and 2-3 feet deep on the shoulder of one foot deep furrow, subsequent filling with silt and transplanting of forest/fruit saplings. This technique provides initial escape from the bad effects of salinity / sodicity until plants become more salt tolerant over the period. Very useful results were obtained in terms of growth data of plants which indicated 4-5 times more plant height, girth and spread (canopy) compared with plants transplanted on flat without digging holes and filling with silt in salt affected soil.
This is a permanent service offered to the farming community. Soil, water and fertilizer samples of farmers are received and analyzed. The detailed site-specific recommendations on all aspects of soil salinity/ sodicity including better land use and safe utilization of brackish water along with analysis reports are conveyed to the concerned farmers. Farmers also get recommendations and advice through mail, internet and telephone by providing soil and water test reports issued by district laboratories or other organizations. In addition, improved seed of salt tolerant varieties of wheat and rice are also provided to farmers of salt affected lands.
Five Ph.D. students conducted their research at SSRI, Pindi Bhattian and were awarded degree by the University of Agriculture, Faisalabad and ITC, The Netherlands. Similarly, three M.Sc. students completed their research at SSRI and obtained degrees from Switzerland and UAF. Two more Ph.D students/staff members are enrolled, one each at Baha-ud-Din Zikariya University, Multan and Punjab University, Lahore.
One Hundred and Fifty Six (156) research papers/ articles were got published in different journals, newspapers / Ziraat Nama.
Three staff member conducted their research at SSRI under supervision of its scientists and were awarded Ph.D. Degrees by University of Kassel, Germany.
Two training courses for scientists were arranged and seven farmer days were celebrated.