Utilization of Untapped Wood Materials in Combination with Biochar for Economic Profitability and Sustainable Agriculture

概要

Historically, global agricultural development has been mainly focusing on increased productivity rather than the integration of natural resource management with food and nutritional security. Worldwide haphazard use of chemical fertilizers and pesticides increases agricultural productivity since the green revolution of 1960s, with the cost of the environment and society. Therefore, high-level researches are essential to figure out innovative, alternative, environment friendly, sustainable options to decrease the use of costly and non-environmentally friendly chemical fertilizers. Thus, developing more sustainable agricultural practices on a large scale is of supreme importance. Based on the characteristics and properties, wood has possibility to be used for sustainable agricultural production. Wood is fundamentally composed of cellulose, hemicelluloses, lignin, and extracts. The chemical composition of wood varies from species to species, but it is approximately 50% carbon, 42% oxygen, 6% hydrogen, 1% nitrogen, and 1% other elements (mainly calcium, potassium, sodium, magnesium, iron, and manganese) by weight. The new approach using a high C: N ratio organic material such as wood that supplies carbon sources exclusively to various fungi, which contribute to the formation of soil aggregation. The aggregate structures, which possess high air and water permeability and water holding capacity, provide essential functions for plants and microorganisms including fungal and bacterial symbionts, and consequently give fast plant growth and high productivity. Biochar addition in soil has already been recognized as a promising technology as it contributes to improve the soil quality, crop yield, and mitigate climate change. This study intended to evaluate the combined effects of woodchips and biochar on soil quality, crop productivity, and economics of onion (Allium cepa) and sweet corn (Zea mays) production. For experimental investigation, woodchips, biochar, organic fertilizer (OF), arbuscular mycorrhizal fungi (AMF), and gliocladium fungi (GF) were applied to onion and sweet corn production. The experiment was laid out in a randomized block design with three replications and it consisted of six treatments namely, T1 -woodchips + OF, T2 -woodchips + OF + AMF + GF, T3 -woodchips + biochar + OF, T4 -woodchips + biochar + OF + AMF + GF, T5 - biochar + OF, and C (control) - OF. Conventional agro materials as nitrogen, phosphorus, or potassium fertilizer, microelements, growth promoters, pH control chemicals, or other agricultural chemicals were not used. Integrated pest management or other conventional methods were not applied to control pests and diseases; only natural defense system was approached. To minimize soil disturbance, weeds were cut by sickle when they began to race with crops. Vegetable crops generally require frequent irrigation, but irrigation was continued for 1 week from seedling day during the whole life cycle of vegetables. In these contexts, for onion production (Study I) our experimental results revealed that combined application of woodchips, biochar, OF, AMF and GF at T4 treatment showed a significant difference in the growth, yield, soil minerals, and economic profitability as compared to plants grown in control. Another notable significant result is that the onion grown in all treatments contained small amount of nitrate and high amount of sugar, calcium, and potassium compared to conventional practice. Moreover, highest net return and benefit cost ratio were found at T4 treatment. On the other hand, for sweet corn production (Study II) experimental results revealed that combined application of woodchips, biochar, and OF at treatment (T3) obtained the highest corn yield, stalk length, water holding capacity, gross margin, and benefit-cost ratio whereas the lowest yield, stalk length, water holding capacity, gross margin, and benefit-cost ratio were obtained at control. Soil mineral concentrations of N, P, K, and Ca were highest in T4 where as the second highest values was recorded in T3. Another notable significant result is that the sweet corn grown in all treatments contained small amount of nitrate as compared to conventional practice. Furthermore, this new approach is able to achieve significant onion and sweet corn yield on existing land without using any pesticides, fertilizers, or other agricultural chemicals consequently has no adverse environmental impact and thus could be a sustainable approach. Therefore, it can be concluded that combined application of woodchips, and biochar appears as a suitable combination in terms of soil quality, crop productivity, and economics of onion and sweet corn production. This study suggests that combination of woodchips, and biochar, could be a good treatment for sustainable agriculture.