Development and Investigation of Carbon Fertilizer for Sustainable Crop Production

Abstract

Development and adoption of sustainable agricultural practices have become inevitable worldwide. Growing population with changing food and energy demands is increasing pressure on agricultural production systems to produce more but with some limited resources. Chemical fertilizers have substantially increased the crop yield and quality since after their introduction into agricultural system. However, with the passage of time fertilizer use efficiency has decreased to <33% leading to huge economic and environmental challenges. Furthermore, the over dependence on inorganic chemical fertilizers and negligible organic inputs have resulted in significant (50%-75%) loss of indigenous soil organic carbon (SOC) content leading to soil degradation. The soil organic carbon plays an important role in soil fertility, resource use efficiency and crop yield therefore, it is mandatory to improve soil organic carbon content along with nutrient use efficiency. Biochar is a sustainable soil conditioner used for improving soil health. Biochar has shown nutrient sorption, retention and slow-release responses in different experimental settings. Hence, biochar can potentially be used as a nutrient carrier for N fertilizers to improve soil carbon content and thereby the soil health and fertility. In this study, biochar was used to make a biochar-based carbon fertilizer. The cotton stalk (Gossypium hirsutum) biochar was produced by using artisanal biochar production process in Kon-tiki pyrolysis kiln. The biochar was activated by using hydrogen peroxide, citric acid solution and 10% sorghum biomass extract (sorghum biomass extract) solution followed by pH (6.0) adjustment and nitrogen impregnation. The three products were named “BCCF-1: Biochar based Carbon Fertilizer-1” (F2, F3 and F4). Four fertilizers along with a control and pristine biochar were tested by tacking spinach (Spinacia oleracea) as a test plant under glasshouse conditions for 45 days. Plant growth and physiology and soil chemical properties were tested to check the effectiveness of individual fertilizers. The results indicated that the developed fertilizers had no significant effect on shoot length. There was no significant effect of fertilizer application on root/shoot water content and root to shoot ratio. But the leaf thickness was observed to have increased by 140% by F3 with a 28.7% increased SPAD value. The fertilizers had no significant effect on photosynthesis efficiency of the plants. Fertilizer application increased the soil pH but showed no effect on the electrical conductivity of the soil. To conclude, the fertilizer F3 can be considered as best performing fertilizer, having shown an increase in SPAD index and leaf thickness. Further studies are needed to investigate the detailed chemical properties of biochar-based fertilizers and their interaction with other macro-micro nutrients’ availability.