超高产夏玉米田土壤微生物与土壤酶的动态变化

为揭示超高产夏玉米田（产量>15 000 kg·hm^-2）土壤微生物与土壤酶活性动态变化特性，在国家玉米工程技术研究中心（山东）试验场进行夏玉米生长季农田土壤微生物与土壤酶活性研究. 在连续3年产量15 000 kg·hm^-2以上的超高产夏玉米田中选择一块超高产田（HF, 产量为20 322 kg·hm^-2）与常规生产田（CF, 产量为8920.1 kg·hm^-2）进行对比分析，主要测定0～20 cm土层土壤细菌、真菌与放线菌数量及脲酶和转化酶活性. 结果表明：播种后超高产田与常规生产田土壤微生物（细菌、真菌与放线菌）数量均表现出先升高后下降的趋势，超高产田在玉米生长后期土壤微生物数量低于常规生产田，细菌与放线菌表现尤其明显，收获期超高产田B/F值（细菌与真菌数量比）比播种期高2.03倍，比常规生产田高3.02倍，常规生产田收获期与播种期的B/F值变化不显著；超高产田土壤脲酶活性在播种31 d（拔节期）后低于常规生产田，转化酶活性播种58 d（开花期）后快速下降，低于常规生产田.

Dynamic changes of soil microbial populations and enzyme activities in super-high yielding summer maize farmland soil.

To reveal the characteristics of the dynamic changes of soil microbial populations and enzyme activities in super high yielding (>15 000 kg·hm^-2) summer maize farmland soil, a comparative study was conducted in the experimental fields in National Maize Engineering Research Center (Shandong). On the fields with an annual yield of >15 000 kg·hm^-2 in continuous three years, a plot with the yield of 20 322 kg·hm^-2 (HF) was chosen to make comparison with the conventional farmland (CF) whose maize yield was 8920.1 kg·hm^-2. The numbers of bacteria, fungi, and actinomycetes as well as the activities of urease and invertase in 0-20 cm soil layer were determined. The results showed that in the growth period of maize, the numbers of bacteria, fungi, and actinomycetes in the two farmland soils increased first and declined then. At the later growth stages of maize, the numbers of soil microbes, especially those of bacteria and actinomycetes, were lower in HF than those in CF. At harvest stage, the ratio of the number of soil bacteria to fungi (B/F) in HF was 2.03 times higher than that at sowing stage, and 3.02 times higher than that in CF. The B/F in CF had less difference at harvest and sowing stages. The soil urease activity in HF was significantly lower than that in CF at jointing stage, and the invertase activity in HF decreased rapidly after blooming stage, being significantly lower than that in CF.