Soil texture, climate and management effects on plant growth, grain yield and water use by rainfed maize-wheat cropping system: Field and simulation study

In sub-mountain tract of Punjab state of India, maize (Zea mays, L.) and wheat (Triticum aestivum L.) crops are grown as rainfed having low crop and water productivity. To enhance that, proper understanding of the factors (soil type, climate, management practices and their interactions) affecting it is a pre-requisite. The present study aims to assess the effects of tillage, date of sowing, and irrigation practices on the rainfed maize-wheat cropping system involving combined approach of field study and simulation. Field experiments comprising 18 treatments (three dates of sowing as main, three tillage systems as subplot and two irrigation regimes as the sub-subplot) were conducted for two years (2004-2006) and simulations were made for 15 years using CropSyst model. Field and simulated results showed that grain yields of maize and wheat crops were more in early July planted maize and early November planted wheat on silt loam soil. Different statistical parameters (root mean square error, coefficient of residual mass, model efficiency, coefficient of correlation and paired t-test) indicated that CropSyst model did fair job to simulate biomass production and grain yield for maize-wheat cropping system under varying soil texture, date of planting and irrigation regimes.Calibration CropSyst model Date of planting Irrigation Tillage Validation

Integrated effect of transplanting date, cultivar and irrigation on yield, water saving and water productivity of rice (Oryza sativa L.) in Indian Punjab: Field and simulation study

Individual effect of different field scale management interventions for water saving in rice viz. changing date of transplanting, cultivar and irrigation schedule on yield, water saving and water productivity is well documented in the literature. However, little is known about their integrated effect. To study that, field experimentation and modeling approach was used. Field experiments were conducted for 2 years (2006 and 2007) at Punjab Agricultural University Farm, Ludhiana on a deep alluvial loamy sand Typic Ustipsamment soils developed under hyper-thermic regime. Treatments included three dates of transplanting (25 May, 10 June and 25 June), two cultivars (PR 118 inbred and RH 257 hybrid) and two irrigation schedules (2-days drainage period and at soil water suction of 16kPa). The model used was CropSyst, which has already been calibrated for growth (periodic biomass and LAI) of rice and soil water content in two independent experiments. The main findings of the field and simulation studies conducted are compared to any individual, integrated management of transplanting date, cultivar and irrigation, sustained yield (6.3-7.5tha-1) and saved substantial amount of water in rice. For example, with two management interventions, i.e. shifting of transplanting date to lower evaporative demand (from 5 May to 25 June) concomitant with growing of short duration hybrid variety (90 days from transplanting to harvest), the total real water saving (wet saving) through reduction in evapotranspiration (ET) was 140mm, which was almost double than managing the single, i.e. 66mm by shifting transplanting or 71mm by growing short duration hybrid variety. Shifting the transplanting date saved water through reduction in soil water evaporation component while growing of short duration variety through reduction in both evaporation and transpiration components of water balance. Managing irrigation water schedule based on soil water suction of 16kPa at 15-20cm soil depth, compared to 2-day drainage, did not save water in real (wet saving), however, it resulted into apparent water saving (dry saving). The real crop water productivity (marketable yield/ET) was more by 17% in 25th June transplanted rice than 25th May, 23% in short duration variety than long and 2% in irrigation treatment of 16kPa soil water suction than 2-days drainage. The corresponding values for the apparent crop water productivity (marketable yield/irrigation water applied) were 16, 20 and 50%, respectively. Pooled experimental data of 2 years showed that with managing irrigation scheduling based on soil water suction of 16kPa at 15-20cm soil depth, though 700mm irrigation water was saved but the associated yield was reduced by 277kgha-1.Rice Date of transplanting Cultivar Crop duration Irrigation Water saving Crop water productivity