Effects of liquid manure enriched biochars on growth of bread wheat, nutrient uptake and soil quality

The use of biochar produced by the pyrolysis of agricultural wastes for recovery of excess nutrients in dairy manure effluent and application of nutrient-enriched biochar as soil amendment provide a solution both for dairy effluent (DE) and excess plant wastes. Applying enriched biochar to soil will add plant nutrition along with the improvement of many soil properties which are effective in soil functioning. Because, the long-term improvement of soil functioning and the increase of carbon sequestration abilities are very important to ensure the sustainability of agricultural production. Improving the functioning ability of soils for long term and also increasing the carbon sequestration ability of soils are very important in order to ensure the sustainability of agricultural production. In this context, the purposes of this study were to determine the effects of DE enriched different biochar types on i.) wheat growth, ii.) physical, chemical and biological properties and qualities of soils with two different textures. The materials selected as agricultural plant wastes are corncob, bean harvest residue and rice husks. The characteristics of specific surface area, cation exchange capacity of biochar materials and easy availability as a raw material were taken into consideration to determine the row materials selected for the study. Two soils with different textures (loam and sandy loam) have been used as soil material in order to clearly observe the effects of biochar application on soil characteristics. Greenhouse experiments were conducted in two plant growing seasons. Treatments consisted of a factorial combination of three biochar types, five biochar levels (0, 0.5%, 1.0%, 2.0% and 3.0%), and five fertilizer levels (DE, DE+25% of plant requirement (PR), DE+50 of PR, DE+100 of PR and PR) arranged in a divided randomized experimental design with three replicates. All of the biochar types were either saturated with nutrient rich DE or kept unsaturated, while the soils with no addition of biochar types were regarded as control treatment during the study. The fertilizers were applied at the beginning of each season, while biochar types were saturated with DE and applied only at the beginning of the experiment. Bezostaja variety of winter wheat (Triticum aestivum L.) was grown for two seasons and soil sampling was done following each harvest. Nutrient uptake levels of the plants were determined by analysis of sample plants to be taken at the end of each experiment period. Some of soil physical, chemical and biological properties effective in functioning of soils were determined. Soil fertility function was quantified using soil management evaluation framework. In the soil quality assessments, the effects of different biochars on soil fertility function was determined. The effect of biochar on DM yield of wheat varied between two different soils in different growing season. The highest DM yield in both seasons (Kömeç 196 mg plant-1 and Dökmetepe 285 mg plant-1) was obtained with BD3 and BD4 treatments while BD1 treatment caused to the lowest DM production. In the second growing season, the DM yield was increased up to BD3 and almost fixed at the BD4, but higher doses of biochar caused a decline of DM yield in both soils. The decrease in DM yield with BD5 treatment relative to BD4 was 1.3% in Kömeç soil and 4.7% in Dökmetepe soil. The DM yield did not significantly change in BD1, BD2, and BD3 treatments, but after this point the DM yield significantly decreased with the increasing biochar doses. The DM yield in Dökmetepe soil was not significantly different among different biochar doses at the second growing season. The highest DM yield (148 mg plant-1) was found in BD2 treatment while the lowest DM yield (148 mg plant-1) was obtained in BD5 treatment. Soil type, BT, BR and FR had significant effect on water retention and total porosity. In both soil types, total porosity was significantly lower at higher BRs than control. The addition of different biochar types continually increased the AWC both in sandy loam and loamy soils, though the effect was more obvious in the loamy soils. However, comparing the water retention with 2.0 and 3.0% BR relative to the control in the first season, the increase rate of AWC was much higher in sandy loam soil compared to loamy soil. The results revealed that all of the biochar types used in this experiment can be utilized to improve AWC in both sandy loam and loamy soils. Addition of biochars reduced the activity of β-glucosidase enzyme and the decline in activity was higher in sandy loam soil compared to loamy soils. The negative effect of biochar addition to β-glucosidase enzyme activity was greater at the highest application rate of 3.0% than the lower biochar doses. Inorganic fertilizer additions along with effluent enriched biochar had significant on β-glucosidase activity that increased with higher fertilizer additions. Given the importance of β-glucosidase enzyme activity in soil organic matter decomposition, biochar application to soils can be considered a sustainable way of increase in soil organic matter. The results revealed that although the production cost is high biochar can be utilized to obtain sustainable productivity of agricultural lands due to its lasting benefits.