O. S. Tomar

Response of nine forage grasses to saline irrigation and its schedules in a semi-arid climate of north-west India

Traditionally, the degraded lands in arid and semi-arid regions are left for pastures but their forage productivity is low, unstable and unremunerative. Often this results in acute shortages of fodder during the post-monsoon period that can perhaps be partly overcome if the limited saline ground-water resources are effectively utilized to supplement water supplies. Thus, a field experiment was conducted during 1993–1997 on a calcareous soil in a semi-arid part of north-west India (average rainfall 350 mm/annum) to evaluate the suitability of forage grasses to saline irrigation (ECiw 8.5–10.0 dS/m) and optimize its schedule. Grass species included in this experiment were Brachiaria mutica Stapf. Cenchrus setigerus Vahl. Chloris gayana Kunth, Cymbopogon flexuosus, Cynodon dactylon Pers. Echinochloa colonum Link. Panicum antidotale Retz., P. coloratum Linn., P. laevifolium Hack., P. maximum Jacq. (Local wild), P. maximum Jacq. (Cultivated) and P. virgatum. Species those were identified to be the most promising included Panicum laevifolium and P. maximum (both local wild and cultivated) with an annual forage production of 3.43–4.23 Mg/ha. The overall reduction in forage yield with saline irrigation equalled 29 per cent when compared with canal water (ECiw 0.4 dS/m). Scheduling saline irrigation based on climatological approach, i.e. when the ratio of depth of irrigation water (Diw) and cumulative open pan evaporation (CPE) equalled 0.4, was observed to be optimal whereas increased salt accumulation nullified the benefits of enhanced water supplies (Diw/CPE=0.8). Two of the definite advantages of irrigated forages were about three–four-fold increase in productivity as compared with natural/seeded pastures and extension of production period to those of conventional shortages, i.e. during summer months (April–June) when the most nomad populations are forced to migrate to traditionally irrigated areas. Thus, it was concluded that saline water use strategies for rehabilitating arid lands with above grass species would not only render these degraded lands be more productive but also ensure conservation and improvement for long-range ecological security of these lands.

Afforestation techniques and evaluation of different tree species for waterlogged saline soils in semiarid tropics

Long‐term field studies were conducted on about three dozen woody perennial species to develop suitable techniques for afforestation of waterlogged saline soils in arid and semiarid regions of India. The soils of the study area were saline sandy loams with a preponderance of chloride and sulfates of Na+, Ca2+, and Mg2+. The soils initial electrolytic conductivity (ECe) was 36.4 dS m−1 in the upper 30 cm. The water table was shallow, fluctuating between 1.5 m depth to the surface in different seasons of the year, and the water was brackish (average EC was 29.8 dS m−1). Three methods of planting, namely, ridge‐trench, subsurface, and furrow, were compared. The furrow technique provided favorable niches for plant survival and growth and was also the most economical for such soils. Prosopis juliflora, Tamarix sp., Casuarina glauca, Acacia farnesiana, A. nilotica, A. tortilis, and Parkinsonia aculeata were found to be the most promising species for these saline soils. Casuarina glauca and Salvadora oleoides s...

Saline-water irrigation for the establishment of furrow-planted trees in northwestern India

Appropriate tree species and planting methods can help rehabilitation of arid areas — that are characterized by low rainfall, high evapotranspiration demands, highly saline ground waters and calcareous subsoils. The growth of Acacia nilotica and Dalbergia sissoo saplings planted in irrigation furrows in such an arid zone of northwest India was not affected adversely by irrigation with saline water of EC W 10.5 dS m−1. The growth of A. nilotica, measured in terms of sapling survival, plant height and biomass yields, was better than that of D. sissoo. Increasing the period of irrigation from the recommended practice of irrigating only in the first year dry season (October–June) to second and third dry seasons (years) improved the sapling survival, growth and biomass (two-to-three-fold) and water use efficiency (two-to-four fold). Most of the salts added with saline irrigation were accumulated below the irrigation channels and were pushed laterally during the monsoon season. The results indicate that the furrow planting technique could be adopted as an afforestation practice in view of the creation of favourable water and salt regimes and their impact on the establishment of trees saplings. Irrigation water supplies for a minimum of intitially two years after transplanting seemed necessary.

Evaluation of Sowing Methods, Irrigation Schedules, Chemical Fertilizer Doses and Varieties of Plantago ovata Forsk. to Rehabilitate Degraded Calcareous Lands Irrigated with Saline Water in Dry Regions of Northwestern India

To get best economic returns from the degraded calcareous soils, which otherwise remain barren in arid and semi-arid regions of northwestern India due to non-availability of good quality water for irrigation, experiments were conducted for three years cultivating Plantago ovata Forsk. using saline water for irrigation on sandy loam soil. Six different sowing methods were compared, irrigating with saline water of electrical conductivity of 8.6 dS m−1. The yield was better when seeds were sown in dry soil followed by saline irrigation in comparison to when sown in moist soil created by pre-sowing irrigation with saline water. When different frequencies of irrigation were compared using water of low salinity (ECiw 4.0 dS m−1), high salinity (EC 8.6 dS m−1), and providing irrigation with waters of low and high salinity alternately, the average un-husked seed yield was found to be 1102, 885, and 1159 kg ha−1, respectively, showing significant advantage when the crop was irrigated alternately with water of low and high salinity. There was increase in yield with increase of frequency of irrigation. Experimentation with different doses of nitrogen and phosphorus fertilizers found that the yield was optimum during first year at 25 kg ha−1 and 50 kg ha−1 during second year. There was an increase in yield when increasing the dose of phosphorus, and there was a significant interaction between nitrogen and phosphorus application. Among eight varieties the best performance was shown by variety JI-4 followed by Sel-10, Niharika, HI-5, GI-2, GI-1, local, and HI-34, in descending order.

Relative Performance of Some Accessions of Casuarina spp. and Silvicultural Practices on Saline Waterlogged Soils in Semiarid Conditions

Field studies in four different sets of experiment on two aspects of Casuarina spp., silvicultural practices and salt tolerance, were conducted at experimental farm Sampla near Rohtak (Haryana) of Central Soil Salinity Research Institute, Karnal, India for 4 to 11 years duration in sandy saline waterlogged soils. Furrow planting method showed better performance over ridge-trench and subsurface planting methods. Tree saplings of 13 months old performed better than 9-month-old saplings. A useful effect of seepage up to 7 m distance from the canal water storage channel on the overall performance of Casuarina equisetifolia was observed due to the dilution effect of salt concentration (from ECe 26.2 to 7.9, 11.1, 13.8, and 19.9 dS m -1 ) in 0-1.2m soil depth at 1, 3, 5, and 7m distance, respectively, and there was virtually no survival beyond 7m distance from the water storage channel. The favorable effect of dilution of salt content boosted the growth of plants positioned near the channel. Performance of six Casuarina accessions (bearing CSIRO seedlot numbers) was studied in one of the sets. C. glauca 13987 showed better performance over the remaining accessions with estimated 71.55Mg ha -1 biomass as compared to 66.03, 47.99, 30.62, 4.59, and 3.56Mg ha -1 by C. glauca 13144, C. obesa 13162, C. equisetifolia 14196, C. obesa 13218, and C. cunninghamiana 13511. Prediction equations for biomass of trees were also derived and approximate R 2 values ranged from 0.82-0.99 which were close to accurate (P = 0.05 and 0.01 levels of significance). A good inverse correlation was observed between tree height ( R = 0.81), diameter ( R = 0.76) of Casuarina equisetifolia and soil salinity. The results provide a sound base for successful afforestation program in sandy saline waterlogged soils by planting promising accessions of Casuarina providing canal water storage channels at a distance of 14m (7m both sides) with older saplings. The promising accessions, such as Casuarina glauca 13987, 13144, and C. obesa 13162, can be grown satisfactorily to ECe 20 dS m -1 .

Salt tolerance and water use by Dalbergia sissoo during the establishment stage

For rehabilitation of soils rendered barren owing to salinity problems, adaptation to site conditions, water use, and multiple uses form the important criteria of tree selection. Therefore, 6‐month‐old saplings of Dalbergia sissoo Roxb. were transplanted in lysimeters (0.45 m diameter and 1.0 m deep) during July 1992 to measure their water use and salinity tolerance during the initial growth stages. These lysimeters were either irrigated with waters of varying salinity levels (ECw = 0.4, 3, 6, and 9 dS m‐1) or the water table was maintained at 0.9‐m depth with the above salinity levels between February 1993 and July 1994. Within 3 months of imposition of the salinity treatments, differences in growth [plant height and diameter at stump height (0.05 m), DSH] became statistically significant. Aboveground biomass per plant monitored in July 1994 was reduced by 29%, 50%, and 63% at ECw of 3, 6, and 9 dS m‐1, respectively, with water table salinity causing greater reductions because of the development of highe...