Effect Of Long-term Fertilization On Soil Microorganism Under Farmland And Greenhouse

The crop production in farmland and vegetable production in greenhouse are important modes of production in northern China, which is the important grain-producing region. Fertilization is one of the main agricultural measures, and reasonable fertilization can improve fertilizer use efficiency and soil conditions to guarantee grain yield stable or increasing. As an important indicator for valuating soil quality, fertility and health degree, the acquaintance of soil microbe can be used to help develop agriculture measures to ensure the continuous production of crops. In this study, on the basis of the long-term experiment located in China Agricultural University Experiment Station of Quzhou County, Handan City, Hebei Province, five consecutive times soil samples from wheat-maize rotation and greenhouse vegetable systems were taken for analysis in2012. A deep studies on the soil physic-chemical properties, the microbial number, community diversity and community structure evolution patterns under different fertilization and planting mode were conducted to investigate the effects of different fertilizer application treatments and planting patterns on soil microbes, expecting to maintain the biodiversity in soil, establish a reasonable greenhouse and field fertilization and management regime, and provide a theoretical basis for maintaining soil quality. The main conclusions are as follows:(1) Effects of different vegetable production systems on greenhouse soil nutrientsThe greenhouse long-term experiment includes3treatments:organic greenhouse (ORG), low input greenhouse (LOW) and conventional greenhouse (CON). Under different vegetable production systems, the soil organic matter, total nitrogen, available phosphorus, potassium content and pH in0-20cm and20-40cm soil layer had the significant different. Compared with CON, ORG and LOW could improve the soil OM, TN, AP and AK content. While compared with LOW, ORG had more obvious effects. In the0-20cm soil layer, compared with CON, OM under ORG and LOW increased by25.1g· kg-1and9.4g· kg-1, respectively; TN by1.4g· kg-1and0.5g· kg-1, respectively; AP by194.7mg· kg-1and125.6mg· kg-1, respectively; AK by289.9mg· kg-1and91.3mg· kg-1, respectively. In20-40cm soil layer, compared with CON, OM under ORG and LOW increased by6.6g· kg-1and2.2g· kg-1, respectively; TN by0.5g· kg-1and0.2g· kg-1, respectively; AP by184.7mg· kg-1and76.7mg· kg-1, respectively; AK by222.7mg· kg-1and85.3mg· kg-1, respectively.(2) Effects of different fertilizer treatments on farmland soil nutrientLong-term fertilization experiment includes four treatments:EM compost (EM); tranditional compost (OF); chemical fertilizer (CF) and unfertilizer (CK). In March, May, June, August and October of2012, soil samples were collected for5times. The results showed that different fertilization treatments had significant effects on soil organic matter (OM), total nitrogen (TN), available phosphorus (AP), available potassium (AK) and pH in0-20cm and20-40cm soil layers. Compared with CK, EM, OF and CF could improve soil OM, TN, AP, AK content and reduce pH. Compared with CF, EM and OF could make more increase of the soil nutrient. In0-20cm soil layer, compared with CK, OM under EM, OF and CF increased by8.4g· kg-1,5.3g· kg-1and1.6g· kg-1, respectively; TN by0.7 g· kg-1,0.5g· kg-1and0.2g· kg-1, respectively; AP by63.6mg· kg-1,59.2mg· kg1and26.6mg· kg"1, respectively; AP by199.7mg· kg-1,142.1mg· kg-1and91.3mg· kg-1, respectively. In20-40cm soil layer, compared with CK, OM under EM, OF and CF increased by2.1g· kg-1,1.0g· kg-1and0.5g· kg-1, respectively; TN by0.2g· kg-1,0.2g· kg-1and O.lg· kg-1, respectively; AP by28.3mg· kg-1,11.7mg· kg-1and4.8mg· kg-1, respectively; compared with CK, AK under EM and OF increased by39.8mg· kg-1and26.1mg· kg-1, respectively, while reduced by5.7mg· kg-1under CF.(3) Effects of different planting patterns on greenhouse soil microbial characteristicsThe results from microbiological studies in greenhouse showed that the soil bacteria and fungi were significantly different under different treatments. The number of bacterial16s rRNA and ITS fungal gene copy numbers under ORG were significantly higher than CON. The bacterial16s rRNA gene copy numbers under different treatments ranged from6.63x109to1.13x1012copies per gram dry soil, higher than fungi ITS gene copies number (3.30x107-1.14x1010copies per gram dry soil). The community structure and diversity of soil bacteria were studied by the T-RFLP approach. The results show that ORG could increase microbial diversity. Firmicutes, Thallobacteria, Bacteroidetes and Proteobacteria are mainly bacteria. Under ORG, LOW and CON, the privileged fungal taxa were132and368bp,138,154,334bp and347bp,134,150,374and466bp, respectively. These showed that different vegetable production systems have different soil microorganism community structure.(4) Effect of different fertilization on farmland soil microbial characteristicsThe results on soil microbiology showed that the soil bacteria and fungi had significant differences under different treatments. The bacteria16s rRNA and fungi ITS gene copy numbers under EM were significantly highest among treatments, and while lowest under CK. Under4treatments, bacterial16s rRNA gene copy numbers ranged from1.83x108to2.33x1011copies per gram dry soil, higher than the fungal ITS gene copy numbers (1.88x106-2.28x109). T-RFLP method was adopted to study the soil bacterial community structure. The results showed that EM compost could significantly increased soil microbial diversity. The results from identification and classification of restriction fragment showed that:Firmicutes, Thallobacteria, Bacteroidetes, Proteobacteria, Cyanobacteria and Tenericutes are mainly bacteria. The relative abundance of fungal fragments with significant differences under different treatments included106,108,134,136,152and173bp. EM and OF could increase the relative abundance of134,173,152and136bp fragment, and reduce the relative abundance of106and108bp. These showed that long-term fertilization treatment could change the soil bacteria and fungi community structures.It is concluded that the different microbial characteristics responding to long-term fertilization on for the detection of changes in soil quality can function as the important indicator. And the existence of large number of microorganisms in soil predicts its potential value in the biochemical processes. This makes solid foundation for the future studies on their roles and statuses in the nutrient cycling process.