Abstract
Biochar application to agricultural soils is rapidly emerging as a new management strategy for its potential role in carbon sequestration, soil quality improvements, and plant growth promotion. The aim of our study was to investigate the effects of biochars derived from white clover residues and poultry manure on soil quality characteristics, growth and N accumulation in maize (Zea mays L.) and wheat (Triticum aestivum L.) grown in a loam soil under greenhouse conditions. Treatments comprised of: untreated control; mineral N fertilizer (urea N, UN) at the rate of 200, and 100 mg N kg-1, white clover residues biochar (WCRB), poultry manure biochar (PMB) at 30 Mg ha–1, and the possible combinations of WCRB+PMB (50:50), UN+WCRB (50:50), UN+PMB (50:50), and UN+WCRB+PMB (50:25:25). The treatments were arranged in a completely randomized design with three replications. Results indicated a significant increase in the growth and biomass production of maize and wheat supplemented with biochars alone or mixed with N fertilizer. Biochars treatments showed varying impact on plant growth depended upon the type of the biochar, and in general plant growth under PMB was significantly higher than that recorded under WCRB. The growth characteristics in the combined treatments (half biochar+half N) were either higher or equivalent to that recorded under full fertilizer N treatment (N200). The biochar treatments WCRB, PMB, and WCRB+PMB (50:50) increased maize shoot N by 18, 26 and 21%, respectively compared to the control while wheat shoot N did not show positive response. The N-uptake by maize treated with WCRB, PMB, and WCRB+PMB (50:50) was 54, 116, and 90 mg g-1 compared to the 33 mg g-1 in the control while the N-uptake by wheat was 41, 60, and 53 mg g-1 compared to 24 mg g-1 in the control. The mixed treatments (half biochar+half N) increased N-uptake by 2.3folds in maize and 1.7 to 2.5folds in wheat compared to the N100 showing increasing effect of biochar on N use efficiency of applied N. Post-harvest soil analysis indicated a significant increase in pH, organic matter, organic C, total N, C:N, and porosity (% pore space) by the added biochars while bulk density (BD) was significantly decreased. The organic matter content in the soil amended with biochars ranged between 19.5 and 23.2 g kg-1 compared to 11.7 and 10.2 g kg-1 in the control and N fertilizer treatments while the BD of biochars amended soils (WCRB, PMB, and WCRB+PMB) was 1.07, 1.17, and 1.11 g cm-3 compared to 1.28 g cm-1 in the control. In summary, the results of present study highlight the agronomic benefits of biochars in improving the quality of the soil, and promoting growth, yield and N accumulation of both maize and wheat with a consequent benefit to agriculture.
Highlights
Soil organic matter (SOM) depletion and its associated effects on soil quality characteristics and fertility status is considered one of the leading environmental threat to agricultural productivity [1, 2]
The problem exist in the most part of the world, but it is especially severe in the heavily populated, under-developed, and ecologically fragile areas of the Hindu Kush Himalaya (HKH) region including the state of Azad Jammu and Kashmir
Effect of single and combined use of biochars with and without N fertilizer on maize (Zea mays L.) growth characteristics is presented in Table 3 and Fig 1
Summary
Soil organic matter (SOM) depletion and its associated effects on soil quality characteristics and fertility status is considered one of the leading environmental threat to agricultural productivity [1, 2]. A substantial amounts of soil and nutrients have been eroded from the sloping uplands due to heavy and irregular rainfall, exposed subsurface layers and capacity of this part to hold nutrients is frailer Under these conditions, soil degradation processes are the major challenges affecting agricultural productivity and food security [1, 3]. Application of organic materials and residues i.e. cover crops, mulches, composts, or manures is considered a common restoration technique that can alleviate the physical conditions of the soils and alter the soil nutrient environment. The benefits of such amendments are, questionable i.e. short-lived because of rapid decomposition and their quality issues. Biochar production and application has received a growing interest and have been proposed a sustainable technology to improve highly weathered or degraded soils, to decrease atmosphere CO2 concentrations, sequester organic C in terrestrial ecosystems for the long-term [11], and to decrease greenhouse gas (GHG) emissions from soils [6]
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