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Mubshar Hussain Muhammad Farooq Ahmad Nawaz Abdullah M. Al-Sadi Zakaria M. Solaiman Salem S. Alghamdi Ume Ammara Yong Sik Ok Kadambot H. M. Siddique 《Journal of Soils and Sediments》2017,17(3):685-716
Purpose
Biochar, the by-product of thermal decomposition of organic materials in an oxygen-limited environment, is increasingly being investigated due to its potential benefits for soil health, crop yield, carbon (C) sequestration, and greenhouse gas (GHG) mitigation.Materials and methods
In this review, we discuss the potential role of biochar for improving crop yields and decreasing the emission of greenhouse gases, along with the potential risks involved with biochar application and strategies to avoid these risks.Results and discussion
Biochar soil amendment improves crop productivity mainly by increasing nutrient use efficiency and water holding capacity. However, improvements to crop production are often recorded in highly degraded and nutrient-poor soils, while its application to fertile and healthy soils does not always increase crop yield. Since biochars are produced from a variety of feedstocks, certain contaminants can be present. Heavy metals in biochar may affect plant growth as well as rhizosphere microbial and faunal communities and functions. Biochar manufacturers should get certification that their products meet International Biochar Initiative (IBI) quality standards (basic utility properties, toxicant assessment, advanced analysis, and soil enhancement properties).Conclusions
The long-term effects of biochar on soil functions and its fate in different soil types require immediate attention. Biochar may change the soil biological community composition and abundance and retain the pesticides applied. As a consequence, weed control in biochar-amended soils may be difficult as preemergence herbicides may become less effective.2.
In a 1-year study, quantification of nitrous oxide (N2O) emission was made from a flood-irrigated cotton field fertilized with urea at 100kg N ha−1 a−1. Measurements were made during the cotton-growing season (May–November) and the fallow period (December–April). Of the total
95 sampling dates, 77 showed positive N2O fluxes (range, 0.1 to 33.3g N ha−1 d−1), whereas negative fluxes (i.e., N2O sink activity) were recorded on 18 occasions (range, −0.1 to −2.2g N ha−1 d−1). Nitrous oxide sink activity was more frequently observed during the growing season (15 out of 57 sampling dates) as compared
to the fallow period (3 out of 38 sampling dates). During the growing season, contribution of N2O to the denitrification gaseous N products was much less (average, 4%) as compared to that during the fallow period (average,
21%). Nitrous oxide emission integrated over the 6-month growing period amounted 324g N ha−1, whereas the corresponding figure for the 6-month fallow period was 648g N ha−1. Subtracting the N2O sink activity (30.3g N ha−1 and 3.8g N ha−1 during the growing season and fallow period, respectively), the net N2O emission amounted 938g N ha−1 a−1. Results suggested that high soil moisture and temperature prevailing under flood-irrigated cotton in the Central Punjab
region of Pakistan though favor high denitrification rates, but are also conducive to N2O reduction thus leading to relatively low N2O emission. 相似文献
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