Georeferenced distribution of micro-secondary nutrients in soils of north central plateau zone of Odisha and identification of soil related production constraints in paddy

GPS based soil samples from five pedons representing different physiography and 650 surface soil samples were collected from 26 blocks of Mayurbhanj under north central plateau zone of Odisha. They were analysed and statistically interrelated following standard procedure to find out the soil nutrient based limiting factors for rice production. The study of vertical distribution of nutrients and soil parameters in pedons revealed that, the pH was acidic and increased down the depth, but, organic carbon content showed the reverse trend and status was medium to low. There were light texture surface soils with clay enriched subsurface layers. The available sulphur status of surface soils was low to marginal (7.5- 15.0 mg/kg) but, below layers were low to very low in status which was due to presence of more organics on the surface. The available Ca2+ and Mg2+ status was found to be sufficient and increase downwards like clay. The DTPA- Zn, Fe, Cu,and Mn status were marginal to adequate in surface and decreased in sub surface layers . But DTPA- Fe status was adequate in pedons. The surface soil samples were mostly acidic (96% )rest samples were neutral to slightly alkaline. The favorable EC (0.1 dS/m) indicated presence of no toxic salt level in soil. Similarly available boron status of soils was marginal to low in 61.23% samples with exceptionally few samples showing adequate values. DTPA- Zn status of 35.53% soils was low to marginal, but DTPA extractable Fe, Mn, and Cu were marginal to adequate in most of the surface soils. Soil acidity, low Organic carbon, CEC and low available S, B, Zn, light texture, were found to be some of the rice yield limiting soil factors of Mayurbhanj district. Adequate supply of deficient plant nutrients like S, B, and Zn and application of organic manure will be beneficial for increasing rice production and productivity of this agroclimatic zone.