Effect Of Sisal Stalks And Residue Return On The Soil Fertility And Sisal Growth

Sisal stalks and residue are the main sideline products,which is rich in resources.Sisal stalks and residue return is one of the important measures to increase production of sisal.But seldom successful reports in the nutrient-release characteristics of sisal stalks and residue in the soil, the effect of improving the soil's ability and the more effective utilization way. In this paper, the physical and chemical properties of soil sampled from the sisal stalks and residue filed will be measured.Sisal stalks combination to Nitrogen and potashfertility will be alsostudied with a pot experiment.And the efficient method to compost with the sisal residen will be studied.In order to reveal the effect of sisal stalks and residue return on the soil fertility and explore the way toimprove the utilization efficiency ofthe sisal residue. Our purpose is to provide technical supports on using the Sisal stalks and residue efficiently.The main findings are as follows:1.The decomposition rates of fresh stalks, dry leaf base and fresh leaf base were82.7%, 57.9% and 34.5%, respectively.The nitrogen releaserates of fresh stalks,dry leaf base and fresh leaf base were 89.2%, 81.3% and 34.0%, respectively. The phosphorusrelease rates of fresh stalks, dry leaf base and fresh leaf base were 84.6%,53.8% and 32.1%, respectively.The potassiumrelease rates of fresh stalks, dry leaf base and fresh leaf base were 94.9%,86.5% and 34.5%, respectively.It needed about four and a half years for a sisal stalk to be decomposedcompletely.All of the decomposition rates of the sisal stalks and the nutrientrelease rates wereincreased fastly early (30d) and slowly in the latter period.The decomposition rates of different parts from more to less in order were fresh stalks, dry leaf base and fresh leaf base.The release ratesof different nutrients from more to less in order wereK>P>N.The nitrogen utilization rate of the crushed sisal stalkswas5.1%whenreturnedalone,and 4.3% when combined with nitrogen fertilizer.The pH, organic mattercontent,total nitrogen content, total phosphorus content, total potassium content, available nitrogen content, available phosphorus content and available potassium content of 0-60cm soil increased after the sisal stalks returning.2. Compared with the controls, the soil pH, organic matter content, total nitrogen content, total phosphorus content, total potassium content, alkali-hydrolyzable nitrogen content, available phosphorus content and available potassium contentsignificantly improved, with sisal stalks return. Among them, the total nitrogen content, organic matter content, available phosphorus content and total phosphorus content increased obviously. With sisal stalks return, soil pH of 0-20cm and 20-40cm soil layers were affected significantly.The organic matter content and alkali-hydrolyzable nitrogen content of 20-40cm and 40-60cm soil layers were affected significantly. Total nitrogen contents of 0-20cm, 20-40cm and 40-60cm soil layers were affected significantly.Total phosphorus content, available phosphorus content, total potassium content and available potassium content of 40-60cm soil layers were affected significantly.3. On the basis of applying phosphorous and potassium fertilizer, the soil organic matter content, alkali hydrolyzable nitrogen content and soil urease activity were significantly higher than in controls, with application of sisal stalks alone, increased by 180.0%, 46.8% and 109.7%, respectively. Soil invertase activity and microbial biomass carbon were significantly higher than in controls, with using the sisal stalks combined with 1/2 amount of urea, increased by 291.2% and 310.7%,respectively.The leaf length of sisal was significantly higher than the controls, the single application of urea and the single application of sisal stalks, with using the sisal stalks combined with 1/4 amount of urea, increased by 60.9%, 25.0%and 22.5%,respectively.4. On the basis of applyingnitrogen and phosphorous fertilizer, the soil pH,organic matter content, alkali hydrolyzable nitrogen and available potassium content were significantly higher than in controls, with using the sisal stalks alone, increased by 3.3%, 162.5%, 56.7% and 33.5%, respectively.Soil catalase activity, urease activity and soil invertase activity were significantly higher than in controls, with using the sisal stalks alone, increased by 11.5%, 100.0% and 494.2%, respectively.Total potassium content of sisal leaf increased significantly with application of sisal stalks.Total potassium content of sisal leaf increased by 61.1% compared to the controls,with application of sisal stalks.5. The decomposition ratio and rate of sisal residue with filling were 50.2% and 214.7 mg/d, increased by 84.6% and 84.6% compared to the controls, under the condition of no adding bacteria agent. Phosphorus release ratio and rate of sisal residue with filling were 67.6% and 0.8mg/d, increased by 225.0% and 300.0%compared to the controls, with adding bacteria agent. Potassium release ratio and rate of sisal residue with filling were 94.6% and 3.5mg/d, increased by 89.6% and 94.4%compared to the controls, under the condition of no adding bacteria agent.The results indicate that the decomposition ratio and rate of sisal residue increased significantly under filling.Howerver, effect of adding bacteria agent was not obvious.The decomposition rates of sisal residue of different nutrients from more to less in order were K>P>N. The field survey results show that thesoil pH, organic matter content,total nitrogen content, total phosphorus content, total potassium content, available potassium content and activity of catalase were higher than the controls, increased by 26.63%, 106.5%, 91.7%, 152.9%, 62.2%, 304.5% and 34.9%, respectively. The results showed that sisal residue return could significantly increase the soil fertility.6.The foul smell of the fermentationproducts became less under the aerobic conditions, and much less after adding the microbial agents or hydrated lime.The decomposition rates of sisalresidueunder aerobic conditionswere bigger thanunder anaerobic fermentation condition, reached 32.2% within 125d, 8.5% higher than the anaerobic fermentation.But the P decomposition rates of anaerobic fermentation was higher than under the aerobic conditions, reached 31.3% within 125d, 45.6% higher than the aerobic conditions.The fermentation brothgermination rates, pH, available nitrogen contentand total potassium contentunder aerobic conditionswere higher than under anaerobic fermentation condition,reach 13.3%?8.04?32.4mg/kg and 0.73g/kg.Total phosphorus content and calcium content of anaerobic fermentation werehigher than under aerobic conditions,reached 26.6g/kg and 128.4 g/kg, increased by 395.8%?156.5% compared to the aerobic conditions.As time passed,thedecomposition rates of sisalresidue, N, P and K release retes were higher before 25d, then slow. Total nitrogen, total phosphorus and total potassium contentwere highest at 100d, respectively. After adding the microbial agents,fermentation broth pH decreased,reached 7.99 under aerobic conditions and 6.14 anaerobic conditions, decreased by 2.1%?12.7%, respectively.Total phosphorus content of fermentation broth increased after adding the microbial agents under anaerobic fermentation,increased by 395.8% compared to the controls.The decomposition rates of sisal residue and total phosphorus content of sisal residue reduced,and total potassium content and the fermentation brothgermination rates increased, after adding hydrated lime.The microbial agents lost its value when use combined with hydrated lime.In summary, the long term return of sisal stalks or residue could effectively improve the soil physical and chemical nature and the soil fertility quality. However,the effects on the soil nutrients and the soil biological activityis were not obvious in the short term. The fermentation production of sisal residue were better after adding bacteria agent and under aerobic fermentation condition at 25d.Bacteria agent should not be mixed with hydrated lime.