Distribution of water extractable heavy metals (Cd, Co, Mn and Mo) in the topsoil of Osijek-Baranja County (Eastern Croatia)
Based on the pedological map of Osijek-Baranja County in eastern Croatia 74 soil samples were collected and analyzed for water extractable heavy metals (Cd, Co, Mn and Mo). By using GIS technique (ArcView software), different set of maps showing the water extractable metals were created. The maps indicate the correlation of water extractable fraction of heavy metals with soil pH, further statistical analysis will be preformed to confirm these assumptions. In addition analysis of variance was conducted to examine the influence of land use and different soil types on water extractable metals. Land use has shown significance for Cd, Co and Mn while soil type for Mo. These results also seem to be pH dependent, as land use and soil type differ in pH which is the factor causing the difference in the concentration of water extractable metals.
Effect of continuous cropping on changes in crop productivity nutrient budgets and soil properties with and without FYM under pearl millet - mustard – cowpea cropping sequence
Long-term field studies are important to generate information on nutrients dynamics which help in understanding nutrients management strategies for sustainable crop productivity. Keeping this in view, the present investigation (2002-07) was carried out in an on-going long term field experiment (started in 1980) to evaluate the effect of continuous cropping on changes in crop productivity, nutrient budget and soil properties with (F1) and without farmyard manure (FYM, F0) under pearl millet- mustard-cowpea (Fodder) cropping sequence. The FYM was applied at 10 t ha-1 once in a year to the kharif pearl millet (F1). Different fertility levels were applied to both FYM treatments: 0 (control, FL0), 50% (FL1), 100% (FL2), and 150% (FL3) of the recommended dose of NP fertilizers (RDF).
The FYM and fertilizer (NP) application increased crops yield over control; however, there was a continuous decline in the productivity of the crops over the years. The overall productivity of pearl millet and mustard grain decreased by 66 and 38%, respectively, in five years over the corresponding yields of 26 and 13.8 q ha-1 in 2002-03 without FYM. A similar decline in crops productivity was also noticed under FL treatments as well as in the control. The inorganic and organic N and P fractions showed depletion over the time in control only. In case of K, all the K fractions showed depletion irrespective of the treatments over the years. The depletion in total K was by 11 and 15 per cent in control and FL2, respectively during five years of cropping over their corresponding content of 7199 and 7964 mg kg-1 in 2002-03. The alone NP fertilization without FYM showed more adverse effect on availability of K, S and micronutrients viz., Zn, Fe and Mn than with FYM treatments.
The study suggested that supplementation of limiting nutrients to provide balanced nutrition to the crops is essential for sustainable higher productivity under intensive cropping on low to medium fertility light textured soils. The use of FYM and inclusion of leguminous crop like cowpea (fodder) in a cropping sequence was found advantageous to utilize soil nutrients more efficiently and to sustain soil fertility and productivity under intensive cropping.
Non-invasive imaging and characterization of absorption, transport and accumulation of cadmium in an intact rice plant
The absorption, transport and accumulation of cadmium (Cd) in rice (Oryza sativa L. cv. Nipponbare) were visualized and characterized quantitatively using the positron-emitting tracer imaging system (PETIS). We developed a method to produce a positron-emitting Cd-107 (half-life: 6.5 hr) tracer by ion-beam bombardment and chemical purification. The tracer was fed to the hydroponic culture and serial images of Cd distribution in the intact rice plants at vegetative stage and grain-filling stage were obtained by PETIS in every four minutes for 36 hours. The images showed that Cd moved up through the root and leaf sheath (vegetative stage) and through the culm to panicles (grain-filling stage) with velocities of a few cm/h. The most characteristic feature of the Cd dynamics was intensive accumulation in the nodes both at vegetative and grain-filling stages. It was found Cd moved from the shoot base into crown roots at vegetative stage. In contrast, no Cd was detected in the leaf blades. These results suggest that xylem-to-phloem transfer is a pivotal step in long-distance transport of Cd from the soil to the grains and the nodes are the most likely organ where the transfer takes place.