Soil enzyme activities and soil microbe population as influenced by long-term fertilizer management during the barley growth in Hunan Province, China

The effects of long-term fertilizer management on soil enzyme activities and soil microbe population under double-cropping paddy fields in southern China was studied. The purpose of this study was to explore the changes of soil enzyme activities and soil microbe population as related to mineral fertilizer and manure and rice residue based on a long-term field experiment. The experiment was initiated in 1986 and consisted of five treatments: without fertilizer (CK), mineral fertilizer (MF), rice residue plus mineral fertilizer (RF), low manure rate plus mineral fertilizer (LOM), and high manure rate plus mineral fertilizer (HOM). The cropping system consisted of barley (Hordeum vulgare L.), early rice (Oryza sativa L.) and late rice. In 2013-2014, soil samples were collected from the 0-20 cm layers to determine soil enzyme activities and soil microbe abundance during barley growth phases. The results indicated that during the barley growing season, the enzyme activities were higher in the HOM, LOM and RF than in the CK. The treatments of HOM, LOM and RF also improved the numbers of aerobic bacteria, actinomycetes and fungi. During barley growth phases, combined application of manure, crop residue and chemical fertilizer improved soil enzyme activities and soil microbe population.   Key words: Alkaline phosphatase, arylamidase, β-glucosidase, Hordeum vulgare L., manure, microbial abundance, mineral fertilizer, rice residue.