Nitrogen dynamics of tropical agroforestry and annual cropping systems

摘要: Abstract The relative importance of the processes SOM (maintenance active soil organic matter) and SYNCHRONY (timing release organically-bound nutrients to coincide with crop demand) were assessed for their contribution maintenance nitrogen availability in alley cropping. Alley cropping is a system agroforestry where trees crops are intercropped, former being periodically pruned produce mulch. Two maize treatments, Erythrina poeppigiana Gliricidia sepium , compared sole-cropped an 8 yr old experiment at CATIE Costa Rica. Maize productivity, N uptake, from mulch residue decomposition measured each month during one cycle. effects changes matter (SOM) on available by measuring field mineralization size microbial pool through season. sub-treatments introduced assess current application uptake (1) removing mulch, (2) applying 15 labelled Monthly sampling biomass, allowed assessment uptake. biomass content, decomposition, all higher than sole 2.2-, 2.8-, 5.0- 2.1-fold respectively. Soil was not significantly different between but increased 80% grown removed contained only 3–15% less maturity. Similarly contributed about 10% N. percentage declined 13–14% 30 days after planting 8–11% 100 planting. Total recovery 10 kg ha −1 almost this taken up 60 weed content 15–24% 7 weeks 2–6% 9 months application. Mulch 3–5% 40 fell zero 105 days. rates under led faster establishment maintained accumulation thereafter. These resulted build readily-mineralizable over yrs tree be related nor inputs. released season accounted 15% increase maize. Transfer may have been restricted low incorporation into biomass. long-term build-up reserve mineralizable more important determining substantially productivity crop.