Three orchard groundcover management systems (GMSs) were established in a newly planted apple (Malus domestica cvs. Liberty, Nova Easygro, and NY84828-12 on Malling 9 rootstock) orchard on a silty-clay loam soil (Aeric Ochraqualf). The GMSs were applied in 2-m-wide strips within tree rows as follows: 1) a 6-cm-thick mulch layer of composed manure, straw, sawdust, and vegetable plant wastes applied in May 1992 and 1994; 2) a “green manure” cover crop of canola (Brassica campestris cv. Humus) seeded in mid-August each year and tilled under the following May; and 3) Post-emergence applications of N-(phosphonomethyl) glycine (glyphosate) herbicide (2.0 kg a.i./ha) in mid-May and July each year. After 3 years of GMS treatments, apple tree growth and trunk cross-sectional area were similar in all three systems. Fruit yield and yield efficiency were greater in glyphosate and compost than in canola GMSs, and `Liberty' was the most productive cultivar. Topsoil N, P, K, Ca, Mg, Zn, and organic matter content were all substantially greater in the compost GMS. Leaf N, K, and P concentrations were consistently greater in trees in compost plots; leaf Ca, Mg, Cu, and Zn concentrations were lower in compost GMS. Weed growth was rank and difficult to control in the compost mulch, but this GMS substantially enhanced orchard soil fertility.
If the inline PDF is not rendering correctly, you can download the PDF file here.