Extractable pool of biochar controls on crop productivity rather than greenhouse gas emission from a rice paddy under rice-wheat rotation

Abstract

The role of extractable pool of biochar in crop productivity and soil greenhouse gas (GHGs) emission is not yet clear. In this study, two biochars with and without extraction was added to a paddy before rice transplantation at 20 t·ha−1. Crop yield, plant traits and greenhouse gas emission monitored throughout a rice-wheat rotation. Between the biochar treatments, changes in bulk density and microbial biomass carbon were insignificant. However, the increase in organic carbon was similar between maize and wheat biochars while higher under bulk wheat biochar than extracted one. The increase in available P and K was higher under wheat than maize biochar regardless of extraction. Moreover, the increase in plant traits and grain yield, in rice season only, was higher under bulk than extracted biochars. Yet, there was no difference in changes in GHGs emission between bulk and extracted biochars regardless of feedstock. Nevertheless, increased methane emission for rice season was lower under extracted biochars than bulk ones. Overall, crop productivity rather than GHGs emission was affected by treatment of extraction of biochars. Thus, use of unextracted biochar is recommended for improving soil crop productivity in the paddy soils.

Effects of Different Biochars on Wheat Growth Parameters, Yield and Soil Fertility Status in a Silty Clay Loam Soil

“…Higher K content values were recorded for TB2 + CF showing increases by 54.1% in grains, of 42.9% in shoots and of 49.7% in roots over the CK group (Figure 3G–I). Our results are consistent with previous studies which reported that plant N, P and K contents improved with the co-application of biochar and chemical fertilizer application under pot and field conditions [5,31,44,45,46]. In present study, TB + CF amendments clearly affected N, P and K contents in grains, shoots and roots of wheat as compared to BB + CF, OB + CF and CF alone.…”

“…Nutrients contents are dependent on the biochar pyrolysis temperature, time and feedstock [2,17,26]. Many studies have reported inconsistent results for crop yield, plant nutrients uptake [1,30,31] and soil properties [10,26]. These variations could be dependent on soil and biochar feedstock properties [32,33].…”

“…The conversion of organic waste into biochar as a soil amendment is a good way to improve plant growth and nitrogen (N) availability as well as reduce losses by leaching [35], having positive effects on soil phosphorus (P) and potassium (K) availability [26,36]. Recent studies have shown that biochar application increased soil enzymes activities in N and P cycling [17,31] but decreases the activities of carbon (C) related enzymes in soil [22,25]. However, some studies have shown inconsistent results [35,37], depending on the soil type [33] and pyrolysis temperature of the biochar [38].…”

“…Soil enzymes are involved in all biochemical reactions [25], metabolism, and the break down and decomposition of organic matter and residues [26]. Furthermore, they accelerate soil nutrients cycling [17,31].…”

Effects of Biochar Amendment on CO2 Emissions from Paddy Fields under Water-Saving Irrigation

“…Heightened global interests—especially in the field of agriculture research—have focused on the biochar, which is derived from biomass by artificial pyrolysis, and its potential to help mitigate global warming, improve crop productivity, and absorb heavy metals [ 7 ]. Some studies have found that biochar has the potential to reduce the decomposition of soil organic matter to counteract the release of CO 2 [ 8 ], increase grain yield, and improve water utilization efficiency [ 9 , 10 ]. The chemical stability of biochar has a carbon sequestration effect, which slows down the greenhouse effect and, thus, can be used as one of the CO 2 emission reduction measures in farmlands [ 11 ].…”