279-8 Organic Orchard Floor Management Impacts On Soil Nitrogen Cycling and Tree Nitrogen Uptake.

Poster Number 1338

See more from this Division: S04 Soil Fertility & Plant Nutrition
See more from this Session: Nutrient Cycling and Management in High Yield Environments: Poster Presentations
Tuesday, October 23, 2012
Duke Energy Convention Center, Exhibit Hall AB, Level 1
Share |

Catherine M. Culumber1, Jennifer Reeve1, Brent Black1, Corey Ransom1, Diane Alston2, Andrew Tebeau2 and Thor Lindstrom1, (1)Plants, Soils, and Climate, Utah State University, Logan, UT
(2)Biology, Utah State University, Logan, UT
Productive capacity in organic peach orchards is dependent on effective management practices that promote the efficient cycling of nitrogen for tree uptake. Total soil nitrogen (N), monthly soil nitrate (NO3-) and ammonium (NH4+), and the natural abundance of N isotopes in peach tree leaves was measured to assess N turnover and tree N uptake among different orchard management treatments. The certified organic peach trial was initiated in 2008 at the Utah Agricultural Experimental Station, Kaysville, Utah and includes six orchard floor treatments: a living-mulch (shallow rooted alyssum) with legume alleyway (LL), living-mulch (shallow rooted alyssum) with grass alleyway (LG), straw-mulch with legume alley (NL), straw-mulch with grass alleyway (NG), tillage (TG) and weed fabric (WG). Biomass inputs from mow and blow contributed an average 225 grams of N to LL and NL treatments in 2011. Total soil N increased significantly across all treatments from 2009 to 2011, and was significantly higher in NL compared to NG and TG treatments in 2011. Soil NO3- was significantly higher in WG in 2009, whereas the LL and NL treatments were highest from 2010-2011, suggesting a cumulative effect of biomass inputs over several seasons. Soil NH4+ was non-significant between treatments. The NG and NL peach trees with straw-mulch had elevated 15N in comparison to other treatments with the same alleyway. Elevated 15N may indicate 15N depleted forms of N are immobilized by straw-mulch or microbial biomass. Significantly lower 15N enrichment in the LL treatment may result from uptake of soil N derived from N2 fixation processes. Differences in soil NO3- and tree leaf 15N abundances may be attributed to immobilization by straw-mulch or microbial biomass, legume mow and blow inputs, or the uptake of legume N exudates by alleyway tree roots, suggesting N uptake and soil N turnover is altered by orchard floor management.
See more from this Division: S04 Soil Fertility & Plant Nutrition
See more from this Session: Nutrient Cycling and Management in High Yield Environments: Poster Presentations