Submitted to: HortScience
Publication Type: Peer reviewed journal
Publication Acceptance Date: 3/4/2010
Publication Date: 4/4/2010
Publication URL: naldc.nal.usda.gov.d2.nal.usda.gov/download/45793/PDF
Citation: Teravest, D., Smith, J.L., Carpenter-Boggs, L., Hoagland, L., Granatstein, D., Reaganold, J. 2010. Influence of orchard floor management and compost application timing on nitrogen partitioning in apple trees. HortScience. 45:637-642. Interpretive Summary: Demand for organically grown food in the United States is growing rapidly and in some sectors, such as fruit, has doubled in the last 3 years. To establish young apple trees significant amounts of soil nutrients needs to be available. Since in organic systems inorganic fertilizer nitrogen cannot be applied there is significant interest in using composts to supply nitrogen. We used compost to fertilize apple trees that were being managed by cultivation, wood chip mulch and legume cover crops to suppress weeds. In the early season nitrogen was consumed by the cover crop and wood chips depleted nitrogen availability to the trees, but later in the season the nitrogen from compost became more available to the trees and increased fertilizer use efficiency. This information is important to growers who are interested in converting to organic grown apples and utilizing efficient fertilization management systems.
Technical Abstract: This study examines the differential partitioning of compost N in young apple (Malus domestica Borkh.) trees under cultivation, wood chip mulch and legume cover crop management. 15N enriched compost was applied to apple trees in April, May and June of 2006 and 2007. Trees were excavated to determine the fate of labeled compost N in September 2007. Trees under wood chips had significantly greater dry weight and N accumulation in vegetative tree components than cultivation or legume cover trees. Partitioning of dry weight and N into fruit was greatest in cultivation trees among all treatments. Fruit yield and compost N-use efficiency were better in the wood chip mulch and cultivation treatments compared to legume cover. Tree reserves were an important source of N for fruit and leaf growth in all treatments, but significantly more so for trees under cultivation. Fruit and leaves were strong sinks for compost N early in the season, but uptake of compost N by legume cover crops and N immobilization in wood chip mulch was elevated in the spring, reducing N uptake and utilization of compost N by apple trees. Later in the season the majority of compost N was partitioned in woody tissues, bolstering N reserves, and N uptake and fertilizer-use efficiency improved.