香蕉-甘蔗轮作对土壤养分含量及酶活性的影响

Effect of Banana-SugarcaneRotation on Soil Nutrient Content and Enzyme Activity

【目的】研究香蕉与甘蔗轮作不同年限后,土壤养分含量和酶活性等指标的变化,从土壤养分层面探索香蕉-甘蔗轮作模式缓解连作障碍机制。【方法】设置两个田间试验,一是连作蕉地轮作甘蔗试验,包括连作多年的蕉地(CK)和连作蕉地轮作甘蔗1年(GZ1)、2年(GZ2)、3年(GZ3)4个处理;二是轮作甘蔗后回种香蕉试验,包括连作蕉地轮作甘蔗2年(GZ2)和轮作2年甘蔗后回植香蕉1年(XJ1)、2年(XJ2)、3年(XJ3)4个处理,测定不同年限养分含量和土壤酶活性等共24个指标。【结果】土壤pH值随着轮作甘蔗年限的增加呈现下降的趋势,随着回种香蕉年限的增加呈现增加的趋势;而土壤转化酶(Inv)、脲酶(Ure)、多酚氧化酶(PPO)、纤维素酶(Cel)等土壤酶活性和有效磷、有效钾、有效硫、有效硼等养分含量则相反,随着轮作甘蔗年限的增加呈现增加的趋势,回种香蕉后呈现下降的趋势;这些指标能较好地反映香蕉-甘蔗轮作过程中土壤质量变化。香蕉枯萎病发病率与土壤pH值呈正相关,与土壤酶中Cel活性与土壤养分中NO3--N、K、S、B含量呈负相关。轮作甘蔗可较好改善土壤质量,其中土壤Inv、Ure、PPO、Cel活性指标GZ2比CK显著升高,土壤养分NO3--N、P、K、S、B含量及Ca/Mg等指标GZ2比CK分别升高146.13%、18.61%、22.70%、45.48%、214.63%和37.64%;连作蕉地轮作甘蔗2年回种香蕉3年后,土壤质量严重恶化,其中土壤Inv、Ure、PPO、Cel活性指标XJ3比GZ2显著下降,NO3--N、S、Zn、B等养分含量指标XJ3比GZ2分别下降45.18%、38.97%、19.05%、72.09%,除Cel活性和AA含量及Ca/Mg指标外,其他指标低于或接近于CK水平。【结论】连作蕉地轮作甘蔗可以提高土壤酶活性和养分含量等改善土壤理化性状,从而缓解香蕉连作障碍;连作蕉地轮作甘蔗2年后土壤理化性状即可得到有效改善,轮作甘蔗2年后回种香蕉3年为宜。

【Objective】The experiment was conducted to explore the changes of soil nutrient contents and enzyme activities after different years of banana-sugarcane rotation and to explore the mechanism of banana-sugarcane rotation mode to alleviate continuous cropping obstacles from soil nutrient level.【Method】Two field trials were conducted to determine a total of 24 indicators(including contents of nutrients and soil enzyme activities etc.)of different years.One was the experiment of sugarcane rotation in banana fields.There were four treatments:continuous cropping bananas for many years(CK),bananas monocropping-1 year of sugarcane rotation(GZ1),bananas monocropping-2 years of sugarcane rotation(GZ2),bananas monocropping-3 years of sugarcane rotation(GZ3).The other was the experiment of replanting bananas after sugarcane rotation.Four treatments were designed as follows 2 years of rotation(GZ2),GZ2-1 year of banana replanting(XJ1),GZ2-2 years of banana replanting(XJ2),GZ2-3 years of banana replanting(XJ3).【Result】The soil pH value showed a decreasing trend with the increase of sugarcane rotation years,and an increasing trend with the increase of banana replanting years.The soil enzyme activities such as soil invertase(Inv),urease(Ure),polyphenol oxidase(PPO),cellulose(Cel),and the available phosphorus(P),available potassium(K),available sulphur(S)and available boron(B)tended to increase with the increase of sugarcane rotation years,and tended to decreased with the increase of bananare planting years.These indicators could better reflect the changes of soil quality during banana-sugarcane rotation.The incidence of banana wilt was positively correlated with soil pH,and negatively correlated with Cel activity,contents of NO3--N,K,S and B in the soil.Sugarcane Rotation could improve soil quality better.Comparing with the CK,the soil invertase,urease,polyphenol oxidase and cellulose activities increased significantly in GZ2,and the contents of NO3--N,P,K,S,B and Ca/Mg increased by 146.13%,18.61%,22.70%,45.48%,214.63%and 37.64%,respectively.After 2 years of rotation and 3 years of replanting banana,however,soil quality deteriorates severely.Comparing with the GZ2,the activities of Inv,Ure,PPO and Cel were significantly decreased in XJ3,the contents of NO3--N,S,Zn and B decreased by 45.18%,38.97%,19.05%and 72.09%,respectively.Except for Cel activity,AA content and Ca/Mg,other indicators were lower or close to those of CK.【Conclusion】Sugarcane rotation of sugarcane in continuous cropping banana in fields can increase soil enzyme activity and nutrient contents and improve soil physical and chemical properties.Therefore,banana continuous cropping obstacles can be alleviated.The soil physical and chemical properties can be effectively improved after continuous cropping of sugarcane for 2 years.After sugarcane rotation for 2 years,then it is advisable to plant bananas for 3 years.