Effect Of Charcoal-Based Fertilizer With Chemical Fertilizer On Soil Physicochemical Characteristics,Growth And Development And Yield Of Cotton

Proper fertilizer application can improve the soil environment,fertilizer utilization and yield,but improper fertilizer application can not only reduce cotton yields and fertilizer utilization,but can also cause a range of environmental problems such as soil caking.To respond to the requirements of green production,we propose green and cost effective fertiliser application measures for cotton with charcoal-based fertilisers with some chemical fertilisers.The effect of charcoal-based fertilisers with chemical fertilisers on cotton growth indicators,photosynthetic characteristics,soil physical and chemical properties,yield quality and economic efficiency was investigated.The experiment was conducted with"Tahe 2"as the test material and six different fertiliser treatments（T1:80%charcoal-based fertiliser+20%fertiliser,T2:60%charcoal-based fertiliser+40%fertiliser,T3:40%charcoal-based fertiliser+60%fertiliser,T4:20%charcoal-based fertiliser+80%fertiliser,T5:100%fertiliser,T6:no fertiliser）in a two-year（2021-2022）one-way randomised block-arranged field trial with the following main findings:（1）As the proportion of carbon based fertilizer application increases,the surface soil porosity gradually increases and the soil bulk density gradually decreases.The contents of alkaline nitrogen,fast-acting phosphorus,fast-acting potassium,and organic matter in the 0-60 cm soil increased first and then decreased with the increase in the proportion of charcoal-based fertilizer with chemical fertilizer,with the highest contents of alkaline nitrogen of 51.87 mg/kg（2021）and 56.23 mg/kg（2022）,fast-acting phosphorus of 54.29 mg/kg（2021）and 66.58 mg/kg（2022）,fast-acting potassium up to 355.67 mg/kg（2021）and 365.67 mg/kg（2022）,and organic matter up to 13.23 mg/kg（2021）and 16.55 mg/kg（2022）,the nutrient content of T2 treatment in each soil layer was significantly increased compared to the treatment with chemical fertilizer alone.（2）Agronomic traits such as plant height,stem thickness and number of leaves increased significantly with increasing rates of charcoal-based fertilizer application throughout the cotton reproductive period.The maximum accumulation rate（Vm）,time to maximum accumulation rate（T）,time to rapid accumulation（t1）and theoretical rapid accumulation amount（Gt）all tended to increase and then decrease with the increase of charcoal-based fertilizer application rate.The average dry matter accumulation,maximum accumulation rate（Vm）and theoretical rapid accumulation（Gt）of the T2 treatment were 77.64 g/plant,1.33 g/（plan·d）,and 52.11 g/plant,respectively.The maximum accumulation rate（T）was 1.75～4.46 days earlier and the time of rapid accumulation（t1）was 1.15～9.32 days later than the treatment with single fertilizer application.（3）The SPAD value,net photosynthetic rate（Pn）,stomatal conductance（Gs）and transpiration rate（Tr）of functional leaves（inverted four leaves before topping and top largest leaves after topping）showed a trend of increasing and then decreasing with increasing the proportion of charcoal-based fertilizer application,and the intercellular carbon dioxide concentration（Ci）of cotton showed a trend of decreasing and then increasing.The maximum functional leaf SPAD values were 64.42 and 65.36 at 90 days after seedling emergence in both 2021 and 2022,respectively.The average Pn,Gs,and Tr maxima and Ci minima over the whole reproductive period occurred in the T2 treatment with 28.23μmol CO₂/（m²·s）,0.45mol/（m²·s）,11.19 mmol/（m²·s）,280.23μmol/mol,respectively.（4）The accumulation of carbon,nitrogen and phosphorus in roots,stalks,leaves,reproductive organs and the whole plant tended to increase and then decrease with the increase in the proportion of charcoal-based fertilizer application.The accumulation of carbon,nitrogen and phosphorus in the whole cotton plant showed a gradual increase as the fertility stage progressed.The accumulation of carbon,nitrogen and phosphorus in roots,stalks,leaves,reproductive organs and the whole plant was the highest in the T2 treatment at all stages of fertility.（5）With the increase of the proportion of charcoal-based fertilizer application,the boll weight,boll number per plant,seed cotton yield and crop yield first increased and then decreased.The highest single boll weight,number of bolls per plant,seed cotton yield,and coat yield were recorded in T2 treatment in2021 and 2022,with two-year averages of 5.85 g,4.95 bolls/plant,6554.46 kg/hm²,and 41.31%,respectively.The average length,length neatness index,specific strength at break,and elongation at break of the upper part of cotton in the T3 treatment were the largest in 2021 and 2022,with a mean value of30.22 mm,85.53%,32.38 CN/tex,and 8.00%in both years,respectively,and the largest clonal value of4.74 in the T2 treatment.Nitrogen fertilizer utilization efficiency,phosphorus fertilizer utilization efficiency,nitrogen fertilizer biased productivity,phosphorus fertilizer biased productivity,nitrogen fertilizer agronomic efficiency,and phosphorus fertilizer agronomic efficiency were the largest in T2 treatment in2021 and 2022,with two-year means of 51.61%,25.12%,29.24 kg/kg,48.48 kg/kg,6.92 kg/kg and 11.48kg/kg,respectively.The T2 treatment had the largest increase benefit in 2021 and 2022 with 4 208.81Yuan/hm²and 6 449.55 Yuan/hm²,respectively.Among the charcoal-based fertilizer with chemical fertilizer patterns,the 60%charcoal-based fertilizer with 40%chemical fertilizer application pattern can improve cotton biomass,nutrient accumulation,yield,improve soil physical and chemical properties,improve economic efficiency,and the best application pattern.