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Waste water from the animal production industry contains large amounts of nitrogen, phosphorus and organic matter, which can easily cause water pollution. Continuous-cropping of Artemisia selengens causes the accumulation of the serious soil-borne pathogen Fusarium oxysporum , resulting in serious disease in cutting seedlings. For the containment of organic matter and the flowability of waste water, the experiment to assay the biocontrol capacity of the waste water fortified with the biocontrol agent Bacillus subtilis D9 against F. oxysporum was performed. The results showed that the population of soil D9 significantly ( P 0.05) affected the Fusarium wilt disease incidence of A. selengens and a higher population of D9 in the soil was correlated with a lower disease incidence of A. selengens . The effects of factors such as the irrigation quantity of treated waste water (TWW), the irrigation quantity of tap water, the percentage of D9 spores, the soil bulk density and the additive ratio of adsorbent in the soil population of Bacillus spp. were determined.The irrigation quantity of TWW, the irrigation quantity of tap water and the additive ratio of poly-γ-glutamic acid were selected as significant factors and were optimized using Central Composite Design. The optimal factors were a TWW irrigation quantity of 2.35 ml cm −2 , a tap water irrigation quantity of 3.21 ml cm −2 , and a poly-γ-glutamic acid additive ratio of 1.11 g L −1 . Validation of the predictive gained population of soil Bacillus was 1.92 × 10 8 cfu g −1 , which was close to the predicted value of 2.0 × 10 8 cfu g −1 . Compared with the control (soil not irrigated with waste water) and WW (soil irrigated with waste water) treatments, the disease incidence with the TWW (soil irrigated with treated waste water) treatment was significantly decreased. The biocontrol efficacy of TWW treatment was 92.5%. TWW significantly decreased the population of F. oxysporum by 47.1% in the rhizosphere soil and by 87.7% in the stem of A. selengens ( P 0.05). These findings support a new value-added application method for waste water from the animal production industry.

In order to identify the principal factors influencing soil water characteristics (SWC) and evaluate SWC effectively, the multivariate-statistical canonical correlation analysis (CCA) method was used to study and analyze the correlation between SWC and soil physical and chemical properties. Twenty-two soil samples were taken from 11 main tobacco-growing areas in Guizhou Province in China and the soil water characteristic curves (SWCC) and basic physical and chemical properties of the soil samples were determined. The results show that: (1) The soil bulk density, soil total porosity and soil capillary porosity have significant effects on SWC of tobacco fiels. Bulk density and total porosity are positively correlated with soil water retention characteristics (SWRC), and soil capillary porosity is positively correlated with soil water supply characteristics (SWSC). (2) Soil samples from different soil layers at the same soil sampling point show similarity or consistency in SWC. Inadequate soil water supply capability and imbalance between SWRC and SWSC are problems of tobacco soil. (3) The SWC of loamy clay are generally superior to those of silty clay loam.