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| Effects of Different Nitrogen Forms on Soil Microorganism Population and Soil
Enzyme Activities around Cucumber Root Zone |
| ZHANG Xue， LIU Shou-wei*， WU Feng-zhi， ZHOU Xin-gang |
| （College of Horticulture，Northeast Agricultural University，Harbin 150030，Heilongjiang，China） |
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Abstract In this paper，seedling pot cultivation experiments were conducted to study the effects of different nitrogen form match on microorganism population and soil enzyme activity in cucumber seedling root zone. This study includes 4 nitrogen form matching treatments as N1（NH4+-N∶NO3--N were 10∶0），N2（NH4+-N∶NO3--N were 7∶3），N3（ NH4+-N∶NO3--N were 5∶5），N4（NH4+-N∶NO3--N were 3∶7）. The same volumes of water were added as the control. The results showed that cucumber seedling dry weight and fresh weight of the N treatments were both higher than the CK，especially the N3 treatment was obviously higher than that of N1，N2 treatments and the CK. The microorganism population of N3 and N4 treatments was higher，among which the population of bacteria and actinomyces were higher than that of N1 treatment and the CK，while the fungus amount was lower than that of all other treatments. N2 treatment had the highest activities of soil urease and neutral phosphatase. N3 treatment had significantly higher soil dehydrogenase activity than the other treatments. In all
treatments the catalase activity was significantly lower than that of the CK. Thus，the conclution: applying nitrogen fertilizer could increase cucumber dry weight，fresh weight，microorganism population and enhance the enzyme activity. Increasing the ratio of nitrate nitrogen could increase cucumber dry weight，fresh weight，soil bacteria and actinomyces population，and also enhance the soil dehydrogenase activity. While increasing the ratio of
ammonium nitrogen could increase soil fungi amount，and enhance activities of urease and neutral phosphatase. Comprehensive evaluation showed that N3 treatment had the best result in greenhouse cucumber cultivation，i.e. the ratio of NH4+-N∶NO3--N is 5∶5 .
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Received: 31 December 2013
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