Nutrients in finger millet and soil at different elevation gradients in Central Nepal

Background Finger millet, a subsistence food crop, is a unique cereal with high nutritional quality particularly in hilly regions in Nepal. Hence, grain nutrients (protein, calcium, and iron percent) of ten different landraces of finger millet and soil quality (SOC, N, P and K) at different altitudes in central Nepal were analyzed. Methods Triplicate finger millet grain samples were collected from ten local landraces cultivated in randomized complete block design (RCBD) experiments at three different elevations (365 m, 1040 m and 1856 m) under the farmer management system for 2 years 2016 and 2017. Similarly, triplicate soil samples were collected from each experiment plot of different elevation. Kjeldahl method was used to determine grain protein and atomic absorption spectrophotometry method was used to determine calcium and iron. Soil nitrogen (N) was estimated by Kjeldahl method, the available phosphorous (P) by a modified Olsen’s method, potassium by Hanway and Heidel method and pH by using digital pH meter. Results The protein calcium and iron content in finger millet grain was significantly different (P < 0.05) among the local landraces and elevation levels. In all landraces of finger millet, the grain protein, calcium and iron content was found to increase along the increasing altitude. An average increase of 3.13% protein was found when altitude increased from 365 to 1856 m. However, only 2.04% and 1.09% of average grain protein increased as elevation increased from 365 m to 1040 m and 1040 m to 1856 m, respectively. The average Ca content increased by 0.47% when altitude increased from 365 to 1856 m. Similarly, the average Ca increased by 0.21% and by 0.26% as altitude increased from 365 m to 1040 m, and 1040 m to 1856 m, respectively and an average 0.33% Fe increase was found from 365 to 1856 m altitude. An increase of 0.11% and 0.21% of Fe was found from 365 to 1040 m and from 1040 to 1856 m, respectively. Soils at all experimental sites were acidic. The SOC, P, K of soil also increased with increasing altitude. Conclusions This study demonstrated the relationship among nutrients in finger millet (proteins, Ca and Fe), soil components (SOC, N, P and K), and altitudes, with respect to ambient climate. The grain nutrients (Nitrogen, Ca and Fe) of finger millet at higher altitudes were found higher than lower altitudes. Similarly, the temperature and grain nutrients showed strong negative correlation with growing season temperature. This study reveals relations of finger millet nutrients with climatic and soil conditions which are crucial to design the promotion policies of nutrient rich local crops in Nepal.