Removal of nitrogen, phosphorus and potassium in the orchard during defoliation | Slāpekļa, fosfora un kālija izneses lapkritī augļu dārzā
2010
Surikova, V., Latvian State Inst. of Fruit-Growing, Dobele (Latvia) | Karklins, A., Latvia Univ. of Agriculture, Jelgava (Latvia). Inst. of Soil and Plant Sciences
Fertiliser planning requires considering different losses of nutrients. For this reason the aim of the study was to determinate losses of nitrogen, phosphorus and potassium during defoliation, related with application of different soil moisture regulation methods. The investigation was done at the Latvia State Institute of Fruit–Growing, Dobele, in 2009, on the basis of an existing field experiment planted in 1997 with cultivar `Melba` (rootstock B9). Three different treatments of soil moisture management were compared: control, sawdust mulch and drip irrigation. Soil was Haplic Luvisol (Hypereutric), sandy loam with agrochemical properties suitable for apple-tree growing. Leaf samples were collected during fall, and analyzed, determining total amount of nitrogen (Kjeldahl method), phosphorous (calorimetrically) and potassium (flame photometry). The content of nitrogen and potassium in the dry matter of fallen leaves was not significantly influenced by the used soil moisture treatment. Significantly higher content of phosphorus was found in leaves in the irrigation treatment. With fallen leaves, 3.0 – 5.5 kg haE-1 P2O5 was removed from the orchard; no significant differences were found among treatments. A significantly larger (p is less than 0.05) amount of nitrogen was lost when using mulch (9.1 kg haE-1). In the control and irrigation treatments removal of nitrogen was only 5.0 to 6.5 kg haE-1 N. Removal of potassium was significantly (p is less than 0.05) influenced by the applied soil moisture regulation method. In the mulch treatment 18.6 kg haE-1 K2O was lost with fallen leaves, while in the control treatment only 10.1 kg haE-1.
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