Soil management practices affect rhizosphere microorganisms and enzyme activities, which in turn influence soil ecosystem processes. The objective of this study was to explore the effects of different nitrogen application rates on wheat (Triticum aestivum L.) rhizosphere soil microorganisms and enzyme activities, and their temporal variations in relation to soil fertility under supplemental irrigation conditions in a fluvo-aquic region. For this, we established a split-plot experiment for two consecutive years (2014–2015 and 2015–2016) in the field with three levels of soil moisture: water deficit to no irrigation (W1), medium irrigation to (70±5)% of soil relative moisture after jointing stage (W2), and adequate irrigation to (80±5)% of soil relative moisture after jointing stage (W3); and three levels of nitrogen: 0 kg ha^–1 (N1), 195 kg ha^–1 (N2) and
270 kg ha^–1 (N3).  Results showed that irrigation and nitrogen application significantly increased rhizosphere microorganisms and enzyme activities.  Soil microbiological properties showed different trends in response to N level; the highest values of bacteria, protease, catalase and phosphatase appeared in N2, while the highest levels of actinobacteria, fungi and urease were observed in N3.  In addition, these items performed best under medium irrigation (W2) relative to W1 and W3; particularly the maximum microorganism (bacteria, actinobacteria and fungi) amounts appeared at W2, 5.37×10⁷ and 6.35×10⁷ CFUs g^–1 higher than those at W3 in 2014–2015 and 2015–2016, respectively; and these changes were similar in both growing seasons.  Microbe-related parameters fluctuated over time but their seasonality did not hamper the irrigation and fertilization-induced effects.  Further, the highest grain yields of 13 309.2 and 12 885.7 kg ha^–1 were both obtained at W2N2 in 2014–2015 and 2015–2016, respectively.  The selected properties, soil microorganisms and enzymes, were significantly correlated with wheat yield and proved to be valuable indicators of soil quality.  These results clearly demonstrated that the combined treatment (W2N2) significantly improved soil microbiological properties, soil fertility and wheat yield on the Huanghuai Plain, China.

This study investigated whether competitive reduction of pathogenic bacteria growth in pond water alleviates lipopolysaccharide (LPS) contamination and improves geese production performances in the “goose-fish” production system, thereby providing the potential for an improved technique for ecological water fowl production. In the first experiment, 240 Magang goslings of 15-d age were randomly and equally allocated into 16 “yard and pond” pens using a 2×2 factorial design with 4 replications per treatment. In the 55-d experimental period, the goslings received 2 main treatments: supplementation of Bacillus subtilis spores in the feed and addition of photosynthetic bacteria (PSB) to the pond water. Both B. subtilis spores and PSB treatments significantly suppressed water counts of Gram-negative bacteria Escherichia coli, Salmonella and Shigella, and LPS concentrations in pond water and in gosling blood (P<0.05). As the result, the two treatments significantly improved gosling weight gain and carcass quality, marked by enhanced breast and leg muscle percentages and reduced subcutaneous fat proportions (P<0.05). Moreover, the improved effects of B. subtilis spores and PSB treatments were additive. In the second experiment, 1 160 adult geese were induced to start egg laying from May throughout the summer months. The geese were separated equally into control and experimental flocks to fit into 2 integration production units, with a density of 1 bird m-2 meter on pond water. Experimental flock geese were treated with B. subtilis spores in feed and PSB in the pond water for the duration of the study. Such treatment combination significantly depressed the growth of E. coli, Salmonella and Shigella in the pond water and reduced LPS concentrations both in pond water and in geese blood (P<0.01). As a result, egg fertility, fertile and set egg hatchabilities were all improved in the treated flock. Results from both growing goslings and breeding geese demonstrated that water bacteria pollution can be competitively reduced by supplementation with B. subtilis spores via the feed and addition of PSB in pond water, each of which reduces LPS contamination to geese and improves production performances. Microecological agents such as B. subtilis spores and PSB improve water quality and provide a simple ecological technique for the “water fowl-fish” integrative production system.