| In five treatments for interplanting green manure as well as clear tilling respectively,soil physical characteres including soil bulk density and moisture content etc. of red soil on young Longan orchard in fixed site were studied, the resut showed that soil bulk density(13.38% and 5.45%% respectively)on surface soil and sub-surface soil decreased, total porosity(15.17% and 9.07% respectively)and pore porostiy (8.16% and 5.09% respectively) on those increased because of interplanting green manure on red soil young Longan orchard, some of soil physical characteristias has been improved which is given as follows; In autumm drought season,interplanting green manure treatment,soil moisture content was higher consened which improved soil moisture condition and improved soil condition including moisture and heat, which promote soil mature on young Longan .orchard.Soil fertility was raised because of interplanting green manure on red soil young Longan orchard. In the soil between rows of the orchard, soil organic matter , humus, huli acid content were much more increased, nitrogen & phosphorus nutrient of the soil was better conserved and available pottassium content was raised on interplanting green manure treatment. In soil under canopy, organic matter humus and huli acid content was obviously raised because of interplanting green manure on the orchard . Meanwhile, exchanged calcium, mangnecium, free iron content, pH value soil between rows and under canopy, have been increasd in varying degree, and the whole phosphorus, available phosphorus, available potassium on the soil under canopy have been raised in varying level.The enzyme activity (except polyphenol oxidase) of surface soil (0-20cm) was higher than those of sub-surface soil(20-40cm),showing that there was obvious different layers in enzyme activity on young Longan orchard . Interplanting green manure were much effectively to raise urease and phosphorylase activity on surface soil between rows, to decrease polyphenol oxidase activity down speed in varying degree,showing that there was little different enzyme activity between H2O2 enzyme and invert enzyme .In surface soil under canopy , soil urease activity in interplantinggreen manure was much to raise ,soil acidity phosphorylase and oyer oxidase activity are to go down, meanwhile , to decrease invert enzyme activity down speed .There wasn't obvious different in sub-surface soil enzyme activity between rows and under canopy. In enzyme activity statistic of 2001, the analysis showed that urease activity value in surface soil under canopy and polyphenol oxidase activity value in surface soil between rows,have very significant different or significant in different treatments .showing interplanting green manure >clear tilling .In the same statistic ,regarding H2O2 enzyme activity in surface soil under canopy , the result was as follows: clear tilling >interplanting green manure . showing very significant different .Meanwhile preliminary approach has been made in this paper regarding relative coefficient of factors between enzyme activity and soil fertility .Except for it, the paper have some studies on the relations of soil fertility and soil enzyme activity.Interplanting green manure could moderate and minimize daily fluctuation of temperature; It increased air temperature (Ta) under canopy 0.2-0.5℃, leaf temperature (T1) 0.2-1.0 ℃ .temperature of surface soil (Ts) 2-3 ℃ and soil temperature in rhizosphere (Tr) 1-2℃ in cool seasons, declined Ta 0.5-0.8℃,Ti 0.4-1.7℃, Ts 8.5℃, Tr4.0℃ respectively in warm seasons. It also lenghthened photosynthetic hours, increased Pn, and significantly decreased soil moisture when green manure grew vigorous in high temperature seasons. It was heplful to filter surplus water in the soil. Besides, it promoted roots growth and nutrient absorption. |
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