Spatial Distribution of Nutrients and Status of Fertility in Arable Greek Soils.
Theodore Karyotis1, Th Mitsimponas2, M Tziouvalekas2, and A Drosos2. (1) National Agricultura; Research Foundation, 1, Theophrastou St., 41335, Larissa, Greece, (2) National Agricultural Research Foundation, Institute for Soil Mapping and Classification, 1 Theophrastou Str., Larissa, 41335, Greece
This study was carried out in soils originated from the wider area of the lake Ascuris which was drained for agricultural use in 1910. Soil fertility has been declined last decades and yields decreased considerably. This investigation is aiming to assess the status of nutrients and the spatial distribution of soil properties. Clay content varied greatly and Cation Exchange Capacity was low at certain locations. The available phosphorus was ranged between 6.0 and 63.0 mg kg–1, and the organic P was much higher. Low available P in some cases exhibits deficiency levels due to empirical application of fertilizers. The soil pH ranged from 5.6 to 7.7 and 23 out of 27 soil samples were acidic. Soil nitrogen was much lower than the mean content observed in lowland Greek soils rich in organic matter. Soil organic carbon varied greatly and increased contents were found in those sites, where soil moisture is usually higher. From the exchangeable cations, the content of Ca++ is the highest and K+ seems to be at deficient level at certain locations. Among micronutrients, the concentration of iron extracted with DTPA was the highest and the rest elements were in the order Mn>Zn>Cu>B. Micronutrients extracted by 4 M HNO3 varied considerably amongst the samples and based on average concentration a different decreasing order was defined: Fe>Mn>Cu>Zn. Close relationships were found between soil carbon, and total soil nitrogen and between soil carbon and CEC. The irregularities in the surface layers may be affected by the kind of deposited material during the process of soil formation, micro relief, cultivation history, hydromorphic conditions and by any factor which affects soil development. Geostatistics have been used for a quantitative depiction in maps of selected properties. These thematic maps can be used by policy makers and institutions for planning and rural development.