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Soil carbon and its fractions are important in understanding the mechanism of soil carbon sequestration. The present study evaluated the impact of seven commercial bamboo species, viz., Bambusa balcooa, B. bambos, B. vulgaris, B. nutans, Dendrocalamus hamiltonii, D. stocksii, and D. strictus, on labile and non-labile carbon fractions. In the 0–15-cm layer, B. nutans had the highest very labile C (7.65 g kg−1) followed by B. vulgaris > B. balcooa > D. stocksii > D. hamiltonii > B. bambos > D. strictus > open. The active carbon pool was significantly low under the control plot (i.e. the open) indicating the positive influence of bamboo in soil C build-up in the top 0–15 cm soil layer. Amongst the different species of bamboo evaluated in this study, D. strictus accumulated the highest active C pool in 0–30-cm soil layer followed by B. vulgaris. Of the total organic C in the 0–30 cm soil depth, majority (55–60%) was contributed by the passive C pool comprising the less labile and the non-labile fraction of SOC. A high value of carbon stratification ratio (> 2) was observed for D. strictus, B. bambos, and D. hamiltonii which proves their potential for restoration of the degraded lands. The majority of bamboo species except for B. balcooa and D. stocksii showed a higher carbon management index than open systems, thereby indicating higher rates of soil C rehabilitation. Of the seven bamboo species, B. vulgaris, D. strictus, and B. nutans can be adopted for cultivation in the northwest Himalayas given their ability to positively impact the SOC and its fractions in both surface and sub-surface soil. [ABSTRACT FROM AUTHOR]

Grewia optiva Drummond is one of important agroforestry tree species grown by the farmers in the lower and mid-hills of western Himalaya. Different models viz., monomolicular, logistic, gompetz, allometric, rechards, chapman and linear were fitted to the relationship between total biomass and diameter at breast height (DBH) as independent variable. The adjusted R values were more than 0.924 for all the seven models implying that all models are apparently equally efficient. Out of the six non-linear models, allometric model (Y = a × DBH) fulfils the validation criterion to the best possible extent and is thus considered as best performing. Biomass in different tree components was fitted to allometric models using DBH as explanatory variable, the adjusted R for fitted functions varied from 0.872 to 0.965 for different biomass components. The t values for all the components were found non-significant (p > 0.05), thereby indicating that model is valid. Using the developed model, the estimated total biomass varied from 6.62 Mg ha in 4 year to 46.64 Mg ha in 23 year old plantation. MAI in biomass varied from 1.66-2.05 Mg ha yr. The total biomass carbon stocks varied from 1.99 Mg ha in 4 year to 15.27 Mg ha in 23 year old plantation. Rate of carbon sequestration varied from 0.63-0.81 Mg ha yr. Carbon storage in the soil up to 30 cm soil depth varied from 25.4 to 33.6 Mg ha. [ABSTRACT FROM AUTHOR]

In a long term study 2009–2018 at ICAR-IISWC, Dehradun, the uniqueness of minor millets based agroforestry systems (AFSs) for effective soil water conservation and biomass production in foot hills of Himalayas were evaluated. The Morus alba (Ma) based AFS was found to be the most productive and profitable system producing 1.1 and 1.8 t ha−1yr−1 of finger millet and wheat grain, respectively besides carbon stocks of 22.9 t ha−1. Morus based agroforestry system produced the highest yield of green fodder and dry fuel wood at 5.1 and 4.5 t ha−1yr−1, respectively after 10 years of planting. The reduction in minor millets yield was offset by the additional production of tree fodder and dry fuel wood by the Multiparous trees (MPTs) in the AFSs. The minimum soil loss was recorded inMa + barnyard millet (BM) based AFS followed byMa + finger millet (FM) at 15.4 and 16.4 t ha−1yr−1 in comparison to cultivated fallow at 25.6 t ha−1. The traditional millets recorded the identical soil loss of 19.7 t ha−1 during the period. The MPTs land use recorded the soil loss of 22.4–22.8 t ha−1. Similarly, the lowest run off was recorded in millet-AFSs ranging from 23.0% to 25.6% than cultivated fallow without crops (38.9%). The highest soil and runoff conservation efficiency was observed in order of AFSs> sole millets > MPTs > cultivated fallow. Millet based AFS led to the improvements in soil physical properties and fertility status significantly.Ma + FM based AFS recorded favourable changes in bulk density (B.D.), water stable aggregates and organic carbon, OC, 0.73%. Grewia optiva + BM recorded the highest OC (0.75%) besides plant nutrients P (183.2%) and K (51.1%) over the cultivated fallow. Agroforestry systems of Ma+FM-wheat and Ma+FM-toria were the most productive and robust systems economically in respect of benefit: cost ratio and net present value. [ABSTRACT FROM AUTHOR]