Impact of Biochar and Zeolite on Agrophysiology of Wheat Grown Under Rainfed Conditions.

Abstract

Low soil fertility, nutrient leaching and moisture retention are the limiting factors contributing in low crop yield in rainfed area. Application of biochar along with zeolite is an innovating soil amendment towards sustainable agriculture and has numerous beneficial effects on soil quality, carbon sequestration, reducing GHG emission and enhancing crop yield by improving fertilizer and water use efficiency. Series of experimental studies were conducted in year 2013-14 and 2014-15 including pot experiment in glass house at Department of Agronomy (PMAS-AAUR) to determine the effect of treatments on crop physiology, yield and moisture retention. Field experiment was conducted at North Pothwar region of Punjab, Pakistan (Koont Research Farm) to explore the effect of biochar and zeolite on wheat yield and soil properties. A Lab experiment was also carried out at Cranfield University, United Kingdom to determine the emission of different volatile compound from soil with and without application of biochar and zeolite. Experimental soil was amended with Dalbergia sissoo wood biochar (B) and Clino ptilolite zeolite (Z) (sole and combine) treatmets which are listed as B0Z0=control, B3=3 tons/ha, B6=6 tons/ha, B9=biochar (9 tons/ha), Z1=zeolite (1 tons/ha), Z3=zeol ite (3 tons/ha), Z5=zeolite (5 tons/ha), B3Z1=biochar (3 tons/ha) + zeolite (1 tons/ha ), B3Z3=biochar (3 tons/ha) + zeolite (3 tons/ha), B3Z5=biochar (3 tons/ha) + zeolite (5 tons/ha), B6Z1=biochar (6 tons/ha) + zeolite (1 tons/ha), B6Z3=biochar (6 tons/ha) + zeolite (3 tons/ha), B6Z5=biochar (6 tons/ha) + zeolite (5 tons/ha), B9Z1=biochar (9 tons/ha) + zeolite (1 tons/ha), B9Z3=biochar (9 tons/ha) + zeolite (3 tons/ha), B9Z5=biochar (9 tons/ha) + zeolite (5 tons/ha). Wheat (Triticum aestivum L.) variety Chakwal-50 was sown on 15th October 2013 and 2014 with seed rate of 130 kg/ha by using randomized complete block design (RCBD) with three replications. Recommended rate of NPK (150:100:60) fertilizers was used and all other cultural practices were kept normal. Wheat plant growth, yield and soil physicochemical properties were studied. The results of two-year pot experiment showed that maximum increase in plant height (18-23 %), leaf area (48-76 %), biological yield (9-14 %) and grain yield (41-47 %) was recorded in B9Z5 treatment over control. It was found that treatment B9Z5 retained 27-29 % more moisture than control up to 16th days after irrigation. It was observed that chlorophyll content and stomatal conductance was increased by 65-66 % and 100 109 % respectively and proline accumulation was 43-53 % lower in treatment B9Z5 with respect to control. Two-year mean values of R2 calculated by regressional analysis of moisture with chlorophyll content (0.858), stomatal conductance (0.775) and proline accumulation (0.840) verify the positive impact of conserved moisture in treatments on plant physiology. In two-year field experiment maximum increase in plant height (20-23 %), number of tillers (23-48 %), 1000 grain weight (59-73 %), biological yield (21-25 %) and grain yield (41-48 %) was found in treatment B9Z5 as compare to control. Moreover, B9Z5 showed maximum increase (5.0-9.0 %) in grain protein content over control. Biochar and zeolite (sole and combined) application with different doses has increased soil organic matter from 0.41-1.25 % in B9Z5 as compared to control Biochar (9 tons/ha) has increased nitrogen by 1.2-2.6 mg/kg, phosphorous by 2.5-7.8 mg/kg and Potassium by 48 137 mg/kg. Likewise, sole zeolite application (5 tons/ha) has increased nitrogen by 0.9-3.0 mg/kg, phosphorous by 3.0-7.3 mg/kg and potassium by 39-128 mg/kg in two years. Whereas, combine treatment B9Z5 showed maximum increase in nitrogen by 0.6-3.8 mg/kg, phosphorous by 1.5-9.6 mg/kg and potassium by 24 186 mg/kg in both experimental years. Similar results were recorded for soil organic carbon. Biochar (9 tons/ha) and zeolite (5 tons/ha) had reduced bulk density by 0.05 g/cm3 and 0.03 g/cm3 respectively, while maximum reduction of 0.1 g/cm3 was found treatment B9Z5 in two years. Maximum increase in water holding capacity was observed in B9Z5 treatment with 39 % increase as compared to control. Biochar (9 tons/ha) and zeolite (5 tons/ha) had significantly decreased ammonia and methane emission from soil while increase in carbon dioxide was observed in treatment B9Z5 over control. It was found that treatment B9Z5 has significantly decreases ammonia emission by 72 %, methane by 36 % and increase carbon dioxide emission by 70 %. Based on economic analysis, it was calculated that use of biochar at the rate of 9 tons/ha and zeolite at the rate of 5 tons/ha in combination has maximum BCR 3.5 during second year. The combine and sole application of biochar and zeolite had positive effects on soil quality and wheat growth, yield and help in reducing greenhouse gasses emission from soil. Therefore, use of biochar and zeolite as a soil amendment can play a significant role in sustaining the yield of wheat crop in rainfed areas.