荒坡地种植巨菌草对土壤微生物群落功能多样性及土壤肥力的影响

研究种植于荒坡地、不同生长年限(1、2、3、5a)的巨菌草对土壤微生物群落功能多样性及肥力的影响。结果表明,不同生长年限巨菌草土壤微生物对不同碳源的利用随培养时间延长而增大,培养72—96 h变化最明显,培养144 h后各土壤AWCD值均达到最大值。总体上AWCD值大小依次为:2年生3年生1年生5年生CK,不同生长年限的巨菌草土壤AWCD值均比对照高,且差异显著,2年生AWCD值最高,其次为3年生,1年生、5年生巨菌草土壤AWCD值差异不显著。对培养96 h土壤微生物利用碳源特性进行主成分分析,31个碳源中提取的与土壤微生物碳源利用相关的主成分8个,其中主成分1至主成分8分别能够解释变量方差的25.39%、18.89%、11.28%、9.31%、6.84%、5.60%、5.26%、4.71%,合计解释变量方差的87.27%;主成分1、主成分2能够区分不同生长年限巨菌草土壤的微生物群落特征,2年生、3年生巨菌草土壤微生物功能多样性与CK相比,差异显著;与主成分1显著相关的碳源主要是糖类,氨基酸,羧酸和多聚物,与主成分2显著相关的碳源主要是氨基酸。不同生长年限的巨菌草的Shannon(H)、均匀度、Brillouin指数均高于CK,且差异显著,2年生与3年生差异不显著,1年生与5年生差异不显著。总体上不同生长年限巨菌草的土壤的pH值、有机质、碱解氮、有效磷、速效钾的含量比对照高,其中3年生巨菌草的土壤有机质含量比对照高98.20%,5年生巨菌草土壤的碱解氮含量比对照高93.2%;除1年生巨菌草外,有机质、碱解氮含量均与对照差异显著。在荒坡地种植巨菌草,可增加土壤微生物群落功能多样性,在一定程度上提高土壤肥力,荒坡地种植巨菌草能产生一定的生态正效应。

Effects of planting Pennisetum sp. (Giant juncao) on soil microbial functional diversity and fertility in the barren hillside

Introduced from Africa by Fujian Agriculture and Forestry University in 2005, the Giant Juncao ( Pennisetum sp.) had the features of tall, erect, forested with the high annual output of 200-400 t/hm². The crude protein content of the Giant Juncao was 10.8% after growth for 4 weeks, indicating the advantage of developed root system, strong stress resistance and quick growth variety. The Giant Juncao may be used to produce mushroom, fungi forage and forage additives successfully. Now, the Giant Juncao is used to control soil erosion and improve the soil properties. This paper studied the effects of the Giant Juncao on the soil microbial community functional diversity and fertility with different growth years (1, 2, 3 and 5 years) planted in the barren hillside. The results indicated that the utilization of carbon sources by soil microbes increased when culture time prolonged. The most obvious change happened in the culture time of 72-96 h. AWCD (Average Well Color Development) value reached the maximum in the culture time of 144 h. Generally, the order of AWCD value was 2 years> 3 years > 1 year > 5 years> CK. The values of AWCD of the Giant Juncao with different growth year was significantly higher than CK. AWCD was highest when the growth year of the Giant Juncao was 2 years, follow by 3 years. The difference of AWCD between 1 and 5 years was not significant. The principal component in the utilization of carbon source by soil microbes in the growth time of 96 h was analyzed. The results showed that the 8 principal components extracted from 31 carbon source were related to soil microbial carbon source utilization, the 1-8 principal components account for 25.39%, 18.89%, 11.28%, 9.31%, 6.84%, 5.60%, 5.26%, 5.60% of variables variance respectively, and account for 87.27% of the total variables variance. The principal component 1 and 2 could be used to distinguish the characteristics of soil microbial community with different growth years of Giant Juncao. The diversity of soil microbial community of the 2 and 3 years' Giant Juncao was significantly different with CK. The Shannon (H), Evenness and Brillouin indexes of soil microbial community with different growth time of Giant Juncao were significantly higher than CK. The Shannon (H), Evenness and Brillouin indexes of soil microbial community planted with Giant Juncao between 2 and 3 years, 1 and 5 years had no significant differences. Generally, pH value, organic matter, alkali solution nitrogen, effective phosphorus and rapidly-available potassium contents of soil planted with Giant Juncao were higher than CK. The content of organic matter of soil planted with 3 years old Giant Juncao was higher than CK by 98.20%. The content of alkaline hydrolysis nitrogen of soil planted with 5 years old Giant Juncao was higher than CK by 93.2%. The organic matter and alkali solution content of soil planted with 2, 3 and 5 years old Giant Juncao were significantly different to CK. The Giant Juncao planted in barren hillside could enhance soil microbial community functional diversity and improve soil fertility to a certain extent. Planting Giant Juncao in the Barren Hillside had certain positive ecological effect.