Soil nitrogen dynamics in alley cropping and no-till systems on ultisols of the Georgia Piedmont, USA
Source: Agroforestry Systems, Volume 39, Number 1, January 1998 , pp. 31-44(14)
Abstract:On highly-weathered Ultisols of the Georgia (USA) Piedmont, a combination of no-till agriculture and alley cropping presents an option for rapidly increasing soil nitrogen availability while restoring long-term soil fertility. Three years after the establishment of Albizia julibrissin hedgerows and no-till agriculture trials, we measured inorganic soil nitrogen (NO3 -–N and NH4 -–N) and net nitrogen mineralization during a 4-month field study and a 14-day laboratory study . We also measured the influence of tree leaf amendments on grain sorghum production and N uptake. Soil nitrate increased four-fold within two weeks of adding Albizia leaf mulch. Soil ammonium did not increase as rapidly nor to the same extent after tree mulch addition. Averaged over the 4-month study, soil nitrate and ammonium were 2.8 and 1.4 times higher in the alley-cropped than in the treeless no-till plots. Net nitrification and mineralization were no higher in the alley cropping plots, during either field or laboratory incubations. Tree mulch additions enhanced crop biomass production and N uptake 2 to 3.5 times under both high and low soil moisture conditions. Our study demonstrates the dramatic short-term impacts of Albizia mulch addition on plant available nitrogen. Combined with no-till practices, alley cropping with Albizia hedges offers Piedmont farmers an option for reducing reliance upon chemical N fertilizer while improving soil organic matter levels.
Document Type: Research Article
Affiliations: 1: Institute of Ecology, University of Georgia, Athens, Georgia, 30602, USA, Email: email@example.com 2: Department of Crop and Soil Sciences, University of Georgia, Athens, Georgia, 30602, USA, 3: Institute of Ecology, University of Georgia, Athens, Georgia, 30602, USA,
Publication date: January 1, 1998