شماره مطلب: 410

Tillage impacts on soil microbial biomass C, N and P, earthworms and agronomy after two years of cropping following permanent pasture in New Zealand

نویسنده: 
T. Aslam
انتشارات: 
elsevier
تعدات صفحات: 
9
Conversion of pasture land to crop rotation by plow tillage and reversion to pasture for replenishment of nutrients is a commonpractice in New Zealand. It is known that plow tillage decreases soil organic matter and causes biological degradation. Theobjective of this study was to investigate the effects of tillage practices on soil microbial biomass carbon (MBC), microbialbiomass nitrogen (MBN), microbial biomass phosphorus (MBP), and earthworm (Aporrectodea caliginosa) populations usedas indicators of soil biological status and of sustainability of permanent pasture (PP) to crop rotation using different tillagepractices. The experimental site at Massey University (Turitea Campus) was established in 1995, where PP land was convertedto double crop rotation using plow tillage (PT) and no-tillage (NT). Crops were summer fodder maize (Zea mays L.) andwinter oat (Avena sativa L.); and PP was used as a control. Plant establishment and crop yields were similar in NT and PT,although adoption of NT reduced weed growth. Microbial biomass contents in PP and NT treatments were almost twice asmuch in 0±5 cm depth soil as in 5±10 cm depth soil. No quantitative differences occurred between 0±5 and 5±10 cm depths inthe PT treatment. Conversion of PP to PT cropping resulted in a 45% decline in MBC, 53% in MBN and 51% in MBP in the0±5 cm soil layer. Microbial biomass content ratios in the 5±10 cm layer did not differ signi®cantly among the tillage practicesand cropping regimes. At 0±10 cm depth, concentrations of MBC, MBN and MBP were signi®cantly higher in the PP and NTthan in the PT treatment. MBC and MBN levels in autumn were signi®cantly higher than in summer and winter. Earthwormpopulations and live mass were also signi®cantly higher in the PP and NT than in the PT treatment. It was concluded thatadoption of NT can protect soils from biological degradation and maintain soil quality as compared with PT management.# 1999 Elsevier Science B.V. All rights reserved.
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