Soil amendment with biochar is evaluated globally as a means to improve soil fertility and to mitigate climate change. However, the effects of biochar on soil biota have received much less attention than its effects on soil chemical properties. A review of the literature reveals a significant number of early studies on biochar-type materials as soil amendments either for managing pathogens, as inoculant carriers or for manipulative experiments to sorb signaling compounds or toxins. However, no studies exist in the soil biologyliterature that recognize the observed largevariations ofbiochar physico-chemical properties. This shortcoming has hampered insight into mechanisms by which biochar influences soil microorganisms, fauna and plant roots. Additional factors limiting meaningful interpretation of many datasets are the clearly demonstrated sorption properties that interfere with standard extraction procedures for soil microbial biomass or enzyme assays, and the confounding effects of varying amounts of minerals. In most studies, microbial biomass has been found to increase as a result of biochar additions, with significant changes in microbial community composition and enzyme activities that may explain biogeochemical effects of biochar on element cycles, plant pathogens, and crop growth. Yet, very little is known about the mechanisms through which biochar affects microbial abundance and community composition. The effects of biochar on soil fauna are even less understood than its effects on microorganisms, apart from several notable studies on earthworms. It is clear, however, that sorption phenomena, pH and physical properties of biochars such as pore structure, surface area and mineral matter play important roles in determining how different biochars affect soil biota. Observations on microbial dynamics lead to the conclusion of a possible improved resource use due to co-location of various resources in and around biochars. Sorption and therebyinactivation of growth-inhibiting substances likelyplaysa rolefor increased abundance of soil biota. No evidence exists so far for direct negative effects of biochars on plant roots. Occasionally observed decreases in abundance of mycorrhizal fungi are likely caused by concomitant increases in nutrient availability,reducing theneedfor symbionts.Inthe shortterm,therelease ofavarietyoforganic molecules from fresh biochar may in some cases be responsible for increases or decreases in abundance and activity of soil biota. A road map for future biochar research must include a systematic appreciation of different biochar-types and basic manipulative experiments that unambiguously identify the interactions between biochar and soil biota.

http://www.css.cornell.edu/faculty/lehmann/pictures/publ/SoilBiolBiochem%2043,%201812–1836,%202011%20Lehmann.pdf

Biochar effects on soil biota – A review

Biochar is a carbon-rich coproduct resulting from pyrolyzing biomass. When applied to the soil it resists decomposition, effectively sequestering the applied carbon and mitigating anthropogenic CO2 emissions. Other promoted benefits of biochar application to soil include increased plant productivity and reduced nutrient leaching. However, the effects of biochar are variable and it remains unclear if recent enthusiasm can be justified. We evaluate ecosystem responses to biochar application with a meta-analysis of 371 independent studies culled from 114 published manuscripts. We find that despite variability introduced by soil and climate, the addition of biochar to soils resulted, on average, in increased aboveground productivity, crop yield, soil microbial biomass, rhizobia nodulation, plant K tissue concentration, soil phosphorus (P), soil potassium (K), total soil nitrogen (N), and total soil carbon (C) compared with control conditions. Soil pH also tended to increase, becoming less acidic, following the addition of biochar. Variables that showed no significant mean response to biochar included belowground productivity, the ratio of aboveground : belowground biomass, mycorrhizal colonization of roots, plant tissue N, and soil P concentration, and soil inorganic N. Additional analyses found no detectable relationship between the amount of biochar added and aboveground productivity. Our results provide the first quantitative review of the effects of biochar on multiple ecosystem functions and the central tendencies suggest that biochar holds promise in being a win-win-win solution to energy, carbon storage, and ecosystem function. However, biochar's impacts on a fourth component, the downstream nontarget environments, remain unknown and present a critical research gap.

https://www.onlinelibrary.wiley.com/doi/pdf/10.1111/gcbb.12037

Biochar and its effects on plant productivity and nutrient cycling: a meta‐analysis

Soil microbial populations are immersed in a framework of interactions known to affect plant fitness and soil quality. They are involved in fundamental activities that ensure the stability and productivity of both agricultural systems and natural ecosystems. Strategic and applied research has demonstrated that certain co-operative microbial activities can be exploited, as a low-input biotechnology, to help sustainable, environmentally-friendly, agro-technological practices. Much research is addressed at improving understanding of the diversity, dynamics, and significance of rhizosphere microbial populations and their cooperative activities. An analysis of the co-operative microbial activities known to affect plant development is the general aim of this review. In particular, this article summarizes and discusses significant aspects of this general topic, including (i) the analysis of the key activities carried out by the diverse trophic and functional groups of micro-organisms involved in cooperative rhizosphere interactions; (ii) a critical discussion of the direct microbe–microbe interactions which results in processes benefiting sustainable agroecosystem development; and (iii) beneficial microbial interactions involving arbuscular mycorrhiza, the omnipresent fungus–plant beneficial symbiosis. The trends of this thematic area will be outlined, from molecular biology and ecophysiological issues to the biotechnological developments for integrated management, to indicate where research is needed in the future.

http://www.dzumenvis.nic.in/Microbes%20and%20Plants%20Growth/pdf/Microbial%20co-operation%20in%20the%20rhizosphere.pdf

Microbial co-operation in the rhizosphere

Recently, iron oxide nanoparticles (NPs) have attracted much consideration due to their unique properties, such as superparamagnetism, surface-to-volume ratio, greater surface area, and easy separation methodology. Various physical, chemical, and biological methods have been adopted to synthesize magnetic NPs with suitable surface chemistry. This review summarizes the methods for the preparation of iron oxide NPs, size and morphology control, and magnetic properties with recent bioengineering, commercial, and industrial applications. Iron oxides exhibit great potential in the fields of life sciences such as biomedicine, agriculture, and environment. Nontoxic conduct and biocompatible applications of magnetic NPs can be enriched further by special surface coating with organic or inorganic molecules, including surfactants, drugs, proteins, starches, enzymes, antibodies, nucleotides, nonionic detergents, and polyelectrolytes. Magnetic NPs can also be directed to an organ, tissue, or tumor using an external magnetic field for hyperthermic treatment of patients. Keeping in mind the current interest in iron NPs, this review is designed to report recent information from synthesis to characterization, and applications of iron NPs.

/pdf/synthesis-characterization-applications-and-challenges-of-2ixwf29t2j.pdf

Synthesis, characterization, applications, and challenges of iron oxide nanoparticles

Chitosan as a potential natural compound to control pre and postharvest diseases of horticultural commodities

The potential of biochar and nanoparticles to serve as effective delivery agents for beneficial bacteria to crops was investigated. Application of nanoparticles and biochar as carriers for beneficial bacteria improved not only the amount of nitrogen-fixing and phosphorus-solubilizing bacteria in soil, but also improved chlorophyll content (1.2–1.3 times), cell viability (1.1–1.5 times), and antioxidative properties (1.1–1.4 times) compared to control plants. Treatments also improved content of phosphorus (P) (1.1–1.6 times) and nitrogen (N) (1.1–1.4 times higher) in both tomato and watermelon plants. However, the effect of biochars and nanoparticles were species-specific. For example, chitosan-coated mesoporous silica nanoparticles with adsorbed bacteria increased the phosphorus content in tomato by 1.2 times compared to a 1.1-fold increase when nanoclay with adsorbed bacteria was applied. In watermelon, the situation was reversed: 1.1-fold increase in the case of chitosan-coated mesoporous silica nanoparticles and 1.2 times in case of nanoclay with adsorbed bacteria. Our findings demonstrate that use of nanoparticles and biochar as carriers for beneficial bacteria significantly improved plant growth and health. These findings are useful for design and synthesis of novel and sustainable biofertilizer formulations.

/pdf/engineered-nanoparticles-natural-nanoclay-and-biochar-as-mm164cii.pdf

Engineered Nanoparticles, Natural Nanoclay and Biochar, as Carriers of Plant-Growth Promoting Bacteria

The Connecticut Agricultural Experiment Station was founded in 1875 and has a 147-year history of “Putting Science to Work for Society.” No program exemplifies that core mission more than the Station’s 12-year effort on nanotechnology. This work first started in the realm of nanotoxicology, evaluating the negative effects of these potential emerging contaminants on crop species and in agricultural systems. However, as evidence began increasing that select nanomaterials at appropriate doses and under certain conditions could actually convey some benefit to plant species, work in nano-enabled agriculture began. With an increasing population and a changing climate driving food insecurity, CAES has developed a robust program on the safe and sustainable application of nanotechnology for food production and preservation. Initiatives include novel strategies for crop protection against a range of pathogens; enhancing crop tolerance abiotic stresses such as drought, salinity, and toxic metal contamination; elevating rates of photosynthesis; developing biopolymer-based delivery systems for agrochemicals with much greater efficiency and efficacy; and novel food nanoscale strategies for food preservation. By collaborating with over 30 domestic and international institutions, CAES has and will continue to lead and participate in efforts to combat global food insecurity. 

From nanotoxicology to nano-enabled agriculture: Following the science at the Connecticut Agricultural Experiment Station (CAES)

Use nanoparticles of Cu, Mn, and Zn to suppress soilborne diseases of eggplants and tomatoes

/pdf/effects-of-salinity-and-irrigation-management-on-growth-and-4zs7j2sava.pdf

Wade H. Elmer

Papers

Engineered Nanoparticles, Natural Nanoclay and Biochar, as Carriers of Plant-Growth Promoting Bacteria

From nanotoxicology to nano-enabled agriculture: Following the science at the Connecticut Agricultural Experiment Station (CAES)

Use nanoparticles of Cu, Mn, and Zn to suppress soilborne diseases of eggplants and tomatoes

Effects of Salinity and Irrigation Management on Growth and Nutrient Concentrations in Poinsettia

First Report of Fusarium Wilt of Yellowwood (Cladrastis kentukea) Caused by Fusarium oxysporum in the United States