•Biochar creates habitat and alters the soil environment for microorganisms.•Rapid change in microbial community structure and function after biochar application.•Long-term shifts in microbial ...communities depend on biochar source and soil texture.•Microorganisms are more sensitive to biochar source in sandy than clayey soils.
Soil microbial communities are responsive to biochar amendments. As the residence time of biochar in soil is expected to be hundreds to thousands of years, the changes in microbial community structure and functions could persist for a long period of time. Given that biochar is being applied as a soil amendment in many parts of the world, the long-term consequences for soil microbial communities need to be considered. The objective of this review is to document how biochar creates new habitats and changes the soil environment for microorganisms, which may lead to changes in microbial abundance, community structure and activities. Our meta-analysis revealed that slow pyrolyzed biochars produced from various feedstocks at temperatures from 300°C to 600°C consistently increased some physico-chemical properties (i.e., pH, cation exchange capacity and aggregation) and microbial parameters (i.e., abundance and community structure of microorganisms) in a vast number of soils during short (≤90days) laboratory incubations and longer (1–3years) field studies. The biochar-mediated changes in soil physico-chemical and biological properties appeared to be a function of soil texture and biochar type based on its feedstock and production temperature, which determines key biochar characteristics such as surface area, porosity and pH. Biochars derived from manure or crop residue feedstocks tend to promote microbial abundance more than wood-derived biochars. Biochars derived from wood and other lignocellulosic-rich feedstocks tend to exhibit beneficial effects on soil microbial abundance later (≥60days) than biochars from manure or crop residue feedstocks. Coarse textured soils tend to have less aggregation, lower microbial biomass and lower enzyme activities when amended with slow pyrolyzed biochars produced at high temperatures (>600°C), but these biochars did not affect the physico-chemical and biological properties of clayey soils. Further research is needed to evaluate the magnitude of biochar influence on soil microbial abundance and activities considering (1) the biochar particle size, surface area, porosity, nutrient content and pH, and (2) the soil organic matter (SOM) content and microbial abundance of the soil matrix. Once the microbial activities in the biochar–soil system are understood, they can be manipulated through organic and inorganic fertilizer applications to sustain or improve agricultural crop production.
There is global interest in understanding the prospects for biochar application to agricultural soils. If biochar enhances the availability of nitrogen (N) and phosphorus (P) to crops, this could be ...pivotal in reducing N and P fertilizer inputs to agricultural soils. This review evaluates the soil biochemical cycling of N and P as influenced by biochars with diverse characteristics, and describes the consequences for plant nutrition with respect to the N use efficiency (NUE) and P use efficiency (PUE) of crops grown in biochar-amended soils. Fundamentally, biochar can alter microbial-mediated reactions in the soil N and P cycles, i.e. N2 fixation, mineralization of N and P, nitrification, ammonia volatilization and denitrification. As well, biochar provides reactive surfaces where N and P ions are retained in soil microbial biomass and in exchange sites, both of which modulate N and P availability to crops. Distinctions must be made between biochars derived from manure- and crop residue-based feedstocks versus biochars derived from ligno-cellulosic feedstock, as well as biochars produced at a lower production temperature (<400 °C) versus biochars generated at a higher production temperature (≥600 °C). These factors determine the nutrient retention capacity of biochars when they are applied to soil. For example, low bioavailable N and P concentrations are expected when coarse-textured soil is amended with biochar having a high surface area, necessitating fertilizer application to avoid N and P deficiencies in the crop. Since the biochemical cycling of N and P in biochar-amended soil is affected strongly by biochar × soil interactions, detailed assessment of biochar-induced changes in soil physico-chemical properties and biological processes may improve predictions of how diverse biochars will affect soil fertility and crop nutrition under site-specific conditions.
•Biochar alters soil physico-chemical and biological properties, and nutrient cycling.•Soil N and P dynamics are a function of interactions between biochar type and soil.•N and P cycling is modulated by biochar-induced changes in microbial processes.•Biochar-induced N and P immobilization can be overcome by applying fertilizer.•There is a research gap regarding nutrient use efficiency in biochar-amended soil.
Being the most expensive spice, saffron has great economic importance. This crop grows well in cold arid deserts. Salinity is one of the important limiting factors for the cultivation of this crop. ...However, the use of composted manured and co-composted biochar and fertilizers can play a role in attenuating the salinity stress on this crop. In this two-year field study, manures from three sources: sheep and goat (SG), cow and buffalo (FYM), and poultry (PM) farms, and their co-compost with slow-pyrolyzed wood-derived biochar (B) were used for saffron cultivation in slightly saline (electrical conductivity 1.95 dS m−1) and non-saline soils. Yield and concentration of antioxidants of stigma and bacterial diversity in the rhizosphere of this crop, under salinity and non-salinity conditions, were evaluated. Results revealed that in non-saline soil of first-year crops, all fertilizers decreased the yield of stigma than control by 15–49 % (P ≤ 0.05) but increased the concentration of carotenoids and total polyphenolics (P ≤ 0.05). In saline soil, no difference in yield was observed between treatments for the first-year crop; however, for the second-year crop, as compared to control, PM and FYM significantly increased yield by 41 % and 44 % respectively, whereas FYM also increased the concentration of total polyphenolics (P ≤ 0.05). The FYM fertilizer was found suitable for the yield and quality of saffron stigma for second-year crops in both soils (non-saline and saline). The observed OTUs, Chao1, Fischer, and ACE indexes based on 16 s rRNA metagenomic analysis revealed 2–4 times greater bacterial diversity in the rhizosphere soil of PM-B and SG-B treatments than in the control. Furthermore, 347 bacterial species were found in PM-B- or SG-B-amended soils absent in control treatments.
Barshore is a small village in the Pishin District, Balochistan, Pakistan, with dry summers and cold rainy winters. This is an agrarian region, mostly with orchards of various fruit trees. This study ...investigated the physico-chemical properties and macrofauna of soils under various agricultural management practices of this region. The concentrations of soil organic matter (SOM), soil organic carbon (SOC), nutrients, pH, electrical conductivity, soil texture, and the abundance and number of species of soil macrofauna of the agricultural fields were measured. Fifteen agricultural fields were sampled. Fourteen fields were orchards of apple, apricot or the mixture of apple and apricot trees and one field was a cropland, cultivated with wheat as a monocrop. The orchards were under conservation agricultural practices; whereas, the cropland was under conventional management. These agricultural lands were 2–26 years old. The concentration of soil organic matter (SOM) in the upper 0–10 cm depth of these field sites ranged from 11.6 g kg
−1
to 32.8 g kg
−1
soil. As compared to cropland, orchards had significantly higher concentration of SOM and SOC. A total of 18 soil macrofauna species were found and the most common and abundant were ants (
Monomorium minimum, Camponotus pennsylvanicus, Solenopsis invicta
, and
L
asius
niger
) followed by
Arion
ssp. (Brown Slug) and earthworm
Lumbricus terrestris.
Regression analysis revealed non-significant relationship of the age and the concentration of SOM with the number of macrofauna species and with the concentrations of total mineral nitrogen, bioavailable phosphorus and clay. The existence of ants had no relationship with the concentration of SOM; whereas, existence of
Lumbricus terrestris
tended to had a positive relationship with the concentration of SOM. The field of tree-based intercropping system was 2 years of age since the land was converted from rangeland to a cropland, had two ant species coexisting. This indicates the positive influence of crop diversification on soil macrofauna.
Scrub rangelands support livestock grazing and provide ecosystem services to their inhabitants. The present study was conducted in Chakwal, an important tract of the Pothwar Plateau, which sustains ...herds of small domestic and nomadic ruminants. Urbanization and uncontrolled grazing practices have reduced rangeland productivity and increased soil erosion and resulted in poor land conditions. This study assessed the influence of two years of rangeland protection on aboveground vegetation biomass and the chemical composition of plants and aimed to determine the influence of seasonal grazing on the live-weight gain of small ewes. Using the line intercept method, vegetation data from protected and unprotected plots in 2015 and 2016 were collected at two sites, Dhulli and Begal. Vegetation cover was assessed from images using VegMeasure. Results showed that protected study sites displayed higher vegetation biomass (834 and 690 kg ha
-1
) compared to the unprotected study site (477 and 326 kg ha
-1
) during April and August of both years. In the seasonal grazing trial, the experimental ewes that grazed on protected rangelands showed higher live-weight gain (33–63 g day
-1
) compared to live weight of ewes (17–21 g day
-1
) that grazed on unprotected rangelands during the experimental period of 127 days at both sites. The results suggest that the Chakwal rangeland has tremendous potential to improve vegetation productivity but modern livestock management and seasonal grazing practices are needed to improve carrying capacity and livestock productivity.
This study investigated the influence of sixteen years exclosure from unmanaged grazing on aboveground vegetation biomass, soil organic matter (SOM), soil aggregation and nitrogen (N) mineralization ...in arid shrubland of Baluchistan, Pakistan. Sampling was carried out from three sites along the chronosequence of secondary succession. One site was located at open-for-grazing area (grazed site) and the other two sites were located in the area that is protected since 1998. One of the protected site is more remote from grazing (protected site 1) where the land is less disturbed and has thick vegetation than the other protected site (protected site 2). Results showed a significant difference for aboveground vegetation biomass across sites and was in the order of protected site 1> protected site 2> grazed site. Soil organic matter was 53% and 46% higher in protected sites than grazed site. Aggregates larger than 2mm size were not detected in soil from grazed site but represented 4.5% and 3% of the sample soil profile at the protected site 1 and protected site 2, respectively. Rate of N mineralization was lower in soils at the grazed site as compared to soils at the protected sites. Soil moisture contents were significantly lower at grazed site and showed a strong positive correlation with aboveground vegetation biomass. This study demonstrates that unmanaged grazing severely affected aboveground vegetation biomass, soil organic matter, large-sized soil aggregates, nitrogen mineralization and soil moisture contents. Short term exclosure from grazing (~16 years) can enhance aboveground vegetation biomass and soil quality in terms of soil organic matter accumulation, soil aggregation, retention of soil moisture and nitrogen mineralization in this arid rangeland.
The Thar Desert, Sindh, Pakistan is characterized by low productivity. Besides, economy is based on agriculture, livestock and mining, nevertheless, livestock graze freely on public and private land. ...The aim of this research was to determine biomass production and to evaluate the effects of continuous and seasonal grazing on protected and unprotected plots. A 45 ha protected rangeland area of Hurrabad in the Umerkot Thar desert was selected and divided into three blocks of 15 ha each. Blocks of the same size were also established in unprotected area. The data for vegetation biomass, canopy cover, forage nutrients and weight gain of animals in two seasons (spring and summer) was collected from both protected and unprotected sites. The results showed that biomass significantly increased in summer in both sites. However, the biomass values in protected sites were significantly higher. Similarly, the vegetation cover also seemed to increase in summer in both protected (90.7% ± 0.29%) and unprotected sites (39.2% ± 0.09%). The foliar concentrations of all nutrients varied significantly with season. The average final live-weight gain for does on the protected grazing sites during the 42-day period in spring and the 96 days after the monsoon was almost double that of does grazing on the unprotected site during 2016 and 2017 (
P
< 0.05). The study concludes that the protection of grazing lands during certain periods can lead to better production of vegetation and livestock and improve range conditions.
Balochistan produces more than 40% of the total tomato production of Pakistan. The climate of this province is mostly arid, and agriculture around urban areas commonly depends on wastewater ...irrigation. This study evaluated under groundwater and wastewater irrigation the influence of wood-derived biochar, cow manure and their co-amendment (as 1:1 biochar:manure ratio) at 0.5 kg m
−2
(or 5 t ha
−1
) and 1 kg m
−2
(or 10 t ha
−1
) rate on fruit yield production of tomato, concentration of heavy metals (lead (Pb), copper (Cu), zinc (Zn), nickel (Ni) and chromium (Cr)), nutrient use efficiency (NUE) of heavy metals (calculated as fruit yield/concentration of a given heavy metal in fruits) and the pH, concentration of mineral nitrogen (N) and soluble inorganic phosphorus (P) of tomato-grown soil. As compared to groundwater irrigation, the biomass and yield production was higher under wastewater irrigation. Organic amendments significantly improved yield production and tended to increase soil pH than control under both irrigation treatments. Wood-derived biochar applied at 1 kg m
−2
caused the highest yield under both irrigation treatments. Organic amendments tended to reduce the concentration of Pb, Cu and Cr and increased the NUE of tomato fruits, indicating that fruits require less acquisition of heavy metals per unit yield production. Organic amendments increased the concentration of soluble inorganic P under wastewater irrigation. Our findings suggest that amendment of biochar, manure and their mixture promoted tomato fruit yield under both irrigation treatments, increased NUE of fruits for heavy metals and increased the concentration of soluble P under wastewater irrigation.
Hazarganji Chiltan National Park in Balochistan, Pakistan was established in 1980 and the protected area was further extended in 1998. Large area of this mountain is still open for unmanaged human ...disturbances such as collection of wood for fuel purpose and livestock grazing. Removal of vegetation of rangelands has a significant negative impact on soil organic matter (SOM). This research evaluates litter decomposition in three sites of Hazarganji Chiltan mountain with varying history of human disturbances (unprotected site, young protected site and old protected site). Twigs of
Pistacia khinjuk
with approximately equal weight and length were placed in litter bags of mesh size 2 mm and were buried in 0-5 cm depth in three sites in January. Half of the twigs of each site received rain simulation in April, August, October, November and January while the other half of the twigs were subjected under natural conditions for 15 months. Twigs from each plot of each treatment of each site were collected from soil after every rain simulation in the previous month of experiment and were processed for weight loss assessment. Results showed that weight loss of twigs by decomposition was significantly higher in the soil of unprotected site as compared to other two sites and there was no difference between rain simulation and control treatments except that loss of weight of twigs of unprotected site was higher under control than rain simulation condition. To confirm that SOM was the major controlling factor for the decomposition of litter decay, soils of each site were collected and burned to remove SOM; thereafter, burned soil samples were mixed with homogenous powder of oven-dried native plants, incubated for 6 months and were provided with dissolved organic matter of the soils of each site. Results showed that there was no difference in the decomposition of litter between soils under controlled laboratory condition, which confirmed that SOM was a major controlling factor for the litter decay in soil under field conditions. The pyrosequencing analysis of the DNA of soils collected from three sites revealed the presence of bacterial species
Thermovum composti.
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