1. Introduction
2. Research Programme
3. Achievements
4. Other Divisions

Mining of nutrients by high yielding varieties of crops leads to depletion of macro- as well as micro-nutrients in soil. Therefore, replenishment of nutrients through chemical and/or biological means is essential to restore and maintain soil fertility. Research efforts are being made on integrated plant nutrient management to improve soil fertility, fertilizer use efficiency and reduce cost of production for sustainable and profitable agriculture. Major emphasis is on the efficient use of macronutrients such as N, P and K.  It has been adequately established that out of micronutrients, deficiencies of economic importance in fields prevail in case of Zn, B, and Fe only. Research efforts have been made to devise practices to manage micronutrient deficiencies in different crops.

Soil salinity is a serious problem of agriculture in Pakistan. Salt-affected soils alone occur on more than six million hectares and more than 70% of the tube-wells in saline areas are pumping out brackish water. The problem is more severe in Sindh and Southern Punjab than other parts of the country. In-fact, these problems are threatening the whole production system of arid and semi-arid areas of the third world. These areas are now subjected to severe degradation and desertification. Efforts have been made to learn to live with salinity and make profitable use of saline land and water resources.

The country is also facing severe water shortage over the last several years so there is dire need to save water and use it efficiently. Work is in progress to develop/evaluate water saving technologies and to identify/develop plants with high water use efficiency.[top]

Research Programme

1. Improving soil fertility, fertilizer use efficiency and soil health

2. Screening and selection of salt and drought tolerant plant species/varieties for profitable utilization of saline soils and ground water for plant production

3. Studies on physiology of plants to enhance their tolerance under salt/drought stress

4. Development of Biosaline Agriculture Technology, its demonstration and transfer to end-users

5. Soil physics and hydrology

Soil Fertility, Fertilizer Use Efficiency and Soil Health

Improving N and P fertilizer use efficiency

Urea is the major N fertilizer in Pakistan. However, about 30% of urea-N applied to soil is lost in gaseous form that lowers its efficiency. Ten percent or even higher increase in wheat yield is possible if urea fertilizer is applied after mixing with P fertilizer in 1:1 ratio or with calcium ammonium nitrate fertilizer in 1:1.5 ratio.

Work was carried out to improve N economy and to increase crop yields under normal and stress conditions. The results showed that a good mixture of NH₄ and NO₃ is appropriate for wheat production under saline soils. Plant residues having narrow C/N ratio and that are easily decomposable can substantially replace chemical N fertilizers.

Nitrogen fertilizer loss through denitrification measured from an irrigated wheat-maize cropping system suggested that substantial N loss through this process occurs from irrigated croplands particularly during summer thus appropriate N fertilizer management practices are essential to reduce this loss.

Results of studies carried out to quantify N₂O emissions from cotton and wheat-maize cropping system suggested that high soil moisture and temperature prevailing under flood irrigated systems in Punjab are conducive for N₂O reduction thus leading to low N₂O emission, which is much less than 1 % of the applied fertilizer N

Management of micronutrient deficiencies

Application of Zn and B fertilizers to rice, wheat and cotton can result 10-30 % increase in crop yields. In Zn deficient soils, soil application of 25 kg ZnSO₄ / ha at sowing is enough for 4-5 years for growing rice, wheat and cotton successfully. The use of Zn enriched rice nursery (20 kg Zn/ha to nursery) is the most economical method to cure Zn deficiency with a value cost ratio (VCR) of 1:40. To cure B deficiency in rice, wheat and cotton soils, application of 10 kg of boric acid/ha or 18 kg of borax/ha proved effective for 4-5 years. It was found that in case of cotton, Zn and B as 0.1 % solution can be applied economically along with insecticides through foliar spray. Value cost ratio for B use in these crops has been very attractive particularly in case of cotton in which it ranged from 1:5 to 1:13 by soil application and 1:20 by foliar application.

It was observed that application of B significantly enhanced rice yield, mainly because of increase in the panicle fertility. Application of B also minimized the adverse effects of water stress in crop plants. Severe attack of rust was observed on B-deficient wheat plants exposed to water stress, whereas no incidence of disease was found in the B treated plants.

The work carried out to study the effect of organic matter on micronutrient availability showed that poultry waste not only increased Cu availability to the maize but also increased Cu concentration in soil after maize harvest. Similarly FYM application to wheat also increased micronutrient concentration in plants

Integrated plant nutrient management

The use of industrial by-products like Dicalcium phosphate (DCP), Filter press mud (FPM) indicated that DCP was also a good source of P, while integrating 2/3 P from organic source (FPM) with 1/3 from mineral fertilizer like SSP, resulted in higher crop yield than their individual application.

Application of SSP to wheat and maize after incubating with poultry litter resulted in higher P fertilizer efficiency as it produced significantly higher yield.

Legumes add N to soil through nitrogen fixation whereas green manuring leads to enhancement in soil organic matter content. The preliminary studies in rice area showed that short duration mungbean variety (NM-92) could easily be grown after wheat. After removing mungbean pods, the remaining plant  could be  ploughed under as green manure. In this way, the farmers can obtain additional income and green manuring is expected to reduce the input of chemical fertilizer to rice, for economical crop production and for restoring soil fertility.

Soil health and plant nutrition

Experiments on wheat and maize indicated that under both the plant species, ammonium compared to nitrate nutrition significantly increased the microbial biomass, dehydrogenase activity and aerobic/anaerobic respiration in the rhizospheric soil. The stimulatory effect of NH₄ on rhizospheric microbial activity was mainly via stimulation of the root sugar exudation.

Agricultural lands in Faisalabad were found to be contaminated with several heavy metals including cadmium and uranium. Some heavy metals were also detected in the edible component of many crops. The primary source of these metals was found to be main Rakh Branch canal whereas raw sewage water was the secondary source. Phytoremediation study to decontaminate these lands showed that heavy metals were not in plant-available form and need to be solublized before employing phytoremediation technology

Fertilizer management for salt-affected soils

Nutrient availability in wheat, rice and cotton growing tracts of Punjab was ascertained. Available N was low in 64% wheat soils, 44% rice soils and 22% cotton soils. Available P was low in 83% wheat soils, 33% rice soils and 66% cotton soils. Therefore, fertilization of many salt-affected soils with these nutrients preferably on soil test basis is recommended to obtain economical/good yields of these crops.  Available K was adequate in most of the wheat and rice soils and in more than 80% of the soils under cotton cultivation.

Fertilizer management practices for salt-affected soils have been recommended. Calcium ammonium nitrate is more suitable fertilizer than urea for wheat. Any P fertilizer can be used for wheat because all the P fertilizers tried were not much different in their effectiveness. Phosphoric acid was tried as a new P fertilizer for increasing wheat yield on salt-affected soils and was found superior to single superphosphate. Phosphoric acid of agri. grade is being manufactured by the Sitara Chemical Industries, Faisalabad and is available to the farmers through their dealers in different districts. In case of wheat, whole P in the form of phosphoric acid can be applied either before sowing or with first irrigation.

It was observed that ammonia losses from N fertilizer applied to salt-affected soils were 15 times higher as compared to those applied to normal soils. Press mud, gypsum and calcium chloride amendments were observed to markedly reduce ammonia losses from urea applied to salt-affected soils.

Rhizospheric microbial functions of saline soils

Studies were carried out to isolate, screen, characterize and identify the Exo-polysaccharides (EPS) producing bacteria associated with roots of the crop plants grown under salt stress conditions and to explore their role in improving rhizospheric soil microbial activities for increasing crop yields. Results of the greenhouse and laboratory studies have established that the EPS-producing G+ve bacilli are more prevalent in these soils and inoculation of the bacteria could mitigate negative effects of salinity on growth of the plants by increasing extent of soil aggregation around roots of the plants and also in other ways.

Salt Tolerant Plants

The research group has been able to identify one salt tolerant variety of cotton (NIAB-999) and one salt tolerant variety of wheat (Sarsabz) for salt-affected areas. Two salt tolerant mutants, one each of mungbean and cowpea have also been developed. Mungbean mutants viz., NM-ST-1 and NM-ST-2 (salt tolerant) were crossed with NM-98 and NM-9800, the salt sensitive but well adapted high yielding mungbean cultivars. The selected mutants were successfully intercropped with cotton on saline marginal land (EC = 8 dS m^-1). One cowpea mutant line has also been identified that is early maturing and can tolerate salinity up to EC = 10 dS m^-1. This mutant can also be grown as

a catch crop. It matures within 70-80 days and can fit very well in the cropping systems like cotton after cotton and wheat after rice.

In addition, several plants having an economic value as food, forage, timber or fire wood have been selected for profitable use of salt-affected soils irrigated with brackish water (Table 1). These plants are also playing an effective role in environmental improvement.

Stress Physiology

Screening technique like cell membrane stability in wheat for drought tolerance, thermostability for heat tolerance in maize and dry matter stress tolerance index, seedling stress tolerance index and root length stress tolerance index for salt tolerance in different crops have been developed. Mechanism of stress tolerance in Brassica species, cotton, wheat, sorghum, rice, grasses and guar has also been established. Some physiological and biochemical markers for stress tolerance have also been identified for these crops. It has been shown that exogenous application of ascorbic acid as an antioxidant against oxidative stress is successful in enhancing heat tolerance potential in maize.

This group is also working on oxidative stress in plants as it is related to the development of high temperature/drought/heavy metal tolerance. Wheat, rice, maize and grasses are being used to study the role of oxidative stress defense enzymes such as catalase and superoxide dismutase. Foliar application of glycinebetaine and salicylic acid are effective in increasing the salt tolerance potential in mungbean and sunflower. Similarly, it was also observed that ABA and IAA enhanced the drought tolerance potential in sunflower and barley by adjusting stomatal conductance and transpiration and increasing water use efficiency (WUE).

Development/Demonstration of `Biosaline Agriculture Technology’

A permanent solution to the salinity problem is leaching and drainage which is much expensive so, efforts have been made to learn to live with salinity and make profitable use of saline land and water resources. In this context, a reasonable progress has been made and several plants having an economic value as food, forage, timber or fire wood have been selected for profitable use of salt-affected soils irrigated with brackish water. These plants are also playing an effective role in environmental improvement. This “Biosaline Agriculture Technology” is a low input technology and is

very appropriate under socio-economic conditions of the developing countries for the utilization and improvement of the salt-affected soils and saline water for developing sustainable farming systems involving agroforestry and livestock.

Agro-forestry has been proved as a good system for economically sustainable biomass production  on saline land. Large scale tree/shrub plantation developed at the station includes Eucalyptus camaldulensis, Acacia ampliceps, Acacia nilotica, mesquite (Prosopis juliflora), Parkinsonia, Frash (Tamarix), Neem (Azadirchta indica) and Iple iple. Eucalyptus camaldulensis and Acacia ampliceps proved the best among tree species.

In a provenance-family trial with 120 seedlots belonging to 15 provenances (14 Australian and one Pakistani) of E. camaldulensis, a significant genetic variation between provenances and families-within-provenances was observed. Provenance from DeGrey River (Western Austraila) proved the best, however few individual families from Pakistan had comparable growth. In other trials, 33 seedlots of this species have been established at BSRS-II, Pakka Anna and 45 seedlots were evaluated under sodic conditions at BSRS, Lahore. These tree stands offer a rich genetic base for quality seed production and also for use in tree improvement research programs

The work on value addition to biomass produced on the station includes:

1. Goat rearing activity to convert salt-tolerant fodders/shrub biomass into meat with benefit/cost ratio (BCR) of 1.3

2. Development of low-cost aquaculture technology on saline wasteland using water, with BCR of 1.4

3. Pilot scale production of Eucalyptus oil with indigenously fabricated plant, with BCR of 2.1

During the last few years the station has attained the status of technology development-cum-technology transfer and salt tolerant germplasm seed supply center

The Biosaline Agriculture Technology has been demonstrated on field stations of NIAB and at similar such stations in 10 different countries in the Middle East and North Africa through an IAEA project led by NIAB

Saline Agriculture Farmer Participatory Development Project (SAFPDP)

Water Management

The growth of Kallar grass on a highly salt-affected soil using brackish irrigation water clearly demonstrated improvement in the soil physical, chemical and mineralogical  properties. Hydrological studies using isotopic techniques carried out in Faisalabad area explored the subsurface aquifer characteristics, water chemistry and sources of recharge in different areas causing water-logging and salinity. A technique has been established for screening of high water-use efficient plants (trees, grasses, bushes and crop plants) for dry areas using neutron moisture meter. The relationship of water use efficiency (WUE) with Carbon Isotope Discrimination (D) has also been found useful to screen many plant species for their water-use efficiency. So far, 6 plant species have been screened successfully for their WUE including Leptochloa fusca, Sporobolus arabicus, Eucalyptus camaldulensis, Acacia ampliceps, Barley and Atriplex.

A. ampliceps showed 4-5 times more biomass yield and 5-9 times more water-use efficiency than E. camaldulensis. Large biomass yield and high WUE of Acacia under high salinity and drought conditions distinguish it as a fast growing tree suitable for salt-affected lands in semi-arid to arid areas. On the other hand Eucalyptus, a highly salt and moderately drought tolerant tree is recommended for areas of no water shortage

Presence of significant positive and linear correlations between WUE and carbon isotope discrimination (Δ) of leaf, grain and straw in rice genotypes was used to identify high yielding out of 13 genotypes.  DM38/88 produced the highest grain yield (7277 kg ha^-1) followed by 7168 and 6773 kg ha^-1 by DM-63275 and DM-64198, respectively. These salt tolerant mutants also showed very high WUE or drought tolerance. A mutant having high yield potential under salt and water stress conditions is now being evaluated in the National Uniform Yield Trials for approval as a variety.

Water saving technologies

Fresh water is a scarce commodity and we need to adapt to water crisis reality. The issues are being addressed at NIAB with research on water saving technologies and sustainable use of brackish ground water. The emphasis is on evaluation of different irrigation techniques and cultural practices and selection of suitable crop varieties (ideotypes).

Water saving through various technologies has been found different. For example, it is possible to save water by 25-30% with bed-and-corrugation irrigation, 20% with zero-tillage, 20-25% with laser land levelling and up to 60% with drip irrigation. Experience at NIAB confirms that drip irrigation is the most efficient water saving technology and it saves water up to 60% (compared to flood irrigation) on cotton, up to 20% (compared to furrow irrigation method) on onion and up to 32% on sorghum.

Tree water use

Table 1. Salt tolerance limits, i.e. root zone salinity causing 50% relative-to-control reduction in yield, of plants studied at NIAB using gravel culture