Climate Resilience In Perennial Crops Through Soil Manipulations, A Case Study Of Litchi (Lychee Chinensis)
Climate change is evidenced by increase in extreme weather events including, heat stress, drought and flood. Perennials are though considered relatively hardy to the weather fluctuations but if various exceeds beyond the tolerable limit, it has catastrophic effect. In land logged part of tropics, drought and heat stress are most common expression of climate change for which adaptation mechanism needs to be developed.
Litchi, said to be queen of all fruits, famous for appearance, taste and flavor is largely cultivated in Bihar, Uttarakhand, West Bengal, Jharkhand states and few others sporadic pockets in India. Being very sensitive to climate change, there is needed to explore management practices to induce climate resilience and production sustenance. Soil samples were collected from field of 36 farmers from Muzaffarpur, district of Bihar from the 0-30cm depth. Additional 20 samples from the depth of 0-90cm at each 15 cm incremental depth were collected from the problem area where drying of litchi trees were reported during summer of 2016. Before sampling, the litchi orchards were grouped based on soil manipulations that includes, mulching with litchi leaves, incorporation of FYM @40 to 60 Kg per tree every year, incorporation of pond soil @100-200Kg per tree every alternate year and application of fertilizers at the rate of Nitrogen (0.8 to 1 Kg) and P (0.5 Kg ) per tree. There were variations in terms of application of micronutrients. Soil pH was found in the range of 7.6 to 9.3 higher in case of Muzaffarpur district. The pH range was higher contrary to reported pH requirement of Litchi in most of the literature. In all group available nitrogen was in the very low category ranging from 78 kg/ha to 195 Kg/ha, though relatively higher in orchards receiving FYM. Available P2O5 was in the range of 12 to 82 Kg/ha and available K2O in the range of 60 to 394 Kg/ha. Micronutrients viz Zinc, Copper, Iron and Manganese were deficit in all soils where as Boron and Sulfur were found adequate in some cases. Boron was found in the range of 0.5 to 2.2 ppm where as sulfur was in the range of 10-36 ppm. The performance of litchi during the year of sampling could not be found correlated with the individual nutrients status of soil as performance was more influenced by externalities including weather extremities and bearing behavior of different plants. However soil water holding capacity, soil moisture and soil temperature (5cm and 20cm) was found favorable in orchards receiving FYM and Pond soil. Soil temp was also low (by 2-4◦ C) under mulched condition as compared to orchards receiving only chemical fertilizer. Shallow soil with sand layer below 60-70 cm, extreme dryness led break in capillarity during 2016 and elevated soil temperature coupled with moisture stress were established as reasons for partial drying of litchi trees in orchards receiving only chemical nutrients where as under similar soil depth, no drying of trees was observed from the orchards in which incorporation pond soil or FYM in root zone was routine practice. The climate buffering effect of soil manipulation was further corroborated in terms of better moisture and lower temperature. The delayed response in recovery of drying litchi trees after application of water indicated reduced water conductance of roots under heat stress condition. Therefore soil health management in litchi orchards need integrated approach as evidenced by climate resilience offered by the soil manipulations through application of amendments like FYM, Pond sediment and or Mulching.
Keywords: Climate Resilience, Pond sediment, FYM, Mulching, Integrated soil health management.