2001 Annual Report for FS01-135
Soil Fertility improvement in Fruit Orchards by Windrowing Urban Plant Debris and Poultry Litter
Summary
Poultry litter is applied by organic farmers and others as a nutrient source and to increase soil fertility and organic matter in Florida and other coastal plain states, especially in sandy soils with low organic matter. Nutrient and moisture content of poultry litter varies widely as does application rate, timing, and method. All of these things affect nitrogen loss through volatilization and mineralization, nutrient availability to plants and related pest problems.
When manures are broadcast in fruit orchards, nutrients, especially nitrogen (N) and phosphorus (P), are frequently lost through runoff and leaching, and this can affect ground water quality. Moreover, costs for manure and urban plant debris (UPD) purchases, transportation, and application may eventually restrict continued broadcasting of this renewable resource in perennial fruit and other horticultural crops. But, UPD and broiler and poultry litter (PL) can be applied in side dressings or windrow areas at the dripline of fruit trees to minimize erosional losses of P and achieve maximum use of N in the major root zone. When applied precisely in the prime root zone, instead of broadcast, application costs and rates, as well as leaching, can be reduced.
In this project, UPD will be applied over a layer of broiler poultry litter to non-bearing citrus trees on bedded groves on sandy soils at combined tonnages of 3, 6, and 9 tons per treated acre. The ratios of UPD/PL and the carbon/nitrogen ratios in all treatments will remain constant. In order to compare windrow treatments with a traditional broadcast manure treatment, poultry litter alone will be broadcast at two tons per treated acre at the same rate as the PL applied in the 6 ton/treated acre UPD/PL treatment. Synthetic fertilizer will be applied at rates recommended by the University of Florida within the dripline of trees as a control treatment. Treatments will be applied in two split applications in May and October of each year.
Treatments will be applied to five replicates per treatment (five trees per replicate) for a total of 125 trees arranged in a completely randomized block design. To facilitate comparison of different treatments during field days, each block of five treatments will be established on each of five beds on which trees are planted.