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In recent years, human and anthropogenic activities have generated elevated accumulations of toxic pollutants in the environment. These toxic pollutants become persistent in the environment and constitute major environmental problems by badly disturbing the ecosystems and human health. Pollutants including heavy metals, hydrocarbons, dyes, pesticides, and radionuclides are hard to remove from the environment given that most of them cannot be degraded by chemical and biological means and are eventually indestructible. Several approaches such as soil incineration, precipitation, or/and ion-exchange methods, have been extensively employed, but are expensive and detrimental to the environment. Apart from physicochemical methods, biological methods have also been acknowledged as an alternative remediation process. Fundamentals of these biological approaches are microbial activities through which degradation of pollutants depends. Moreover, the cosmopolitan distribution and significant properties of microorganisms in alteration and detoxification of pollutants make them an ultimate candidate. Among biological methods, biosorption is one of the promising technology for pollutant elimination/recovery from wastewater because of its effectiveness, simplicity, and easy biomass availability. This article critically reviews the mechanism, advantages, limitations, and the significance of biosorption for the removal of heavy metals, radionuclides, dyes, hydrocarbons, and pesticides from the environment.

The hill environments cover about 27% of the total land surface of earth, and the Himalaya lies in North East India, comprised of 65% mountainous area. Agriculture is the primary source of income in hills; however, it has several intrinsic limitations, i.e. inaccessibility, underutilization of natural resources, climatic impact, and environmental limitations. There are various factors affecting the productivity of the hill agroecosystems including soil conditions, change in precipitation, temperature, and climate change in recent years. In addition, nowadays the traditional agriculture practices have been influenced by modernization which have ignored the key resource base of traditional crops in hills and resulted in considerable loss of microbial diversity. Microorganism in soil plays a crucial role in preserving the soil health, its productivity, and allover ecosystem functioning. The diverse population and metabolism of bacteria, fungi, and archaea enhance the availability of essential minerals and trace elements through their complex redox reactions and colonization into the soil. Considering the constrains and limitation of hill agriculture, it is essential to investigate about the microbial functional signatures, viz. energetics and regulatory circuits and structural genes regulating different metabolic pathways, which can directly address to the potential of microbial functions that are related to agroecosystem processes. The advancement in the molecular techniques, viz. high-throughput metagenomics enabling the soil scientists to investigate the microbial communities in detail to harness their potential for productivity of hill agroecosystems.

The growth rate of each plant (dry matter accumulation rate) mainly depends on sun’s energy interception (electromagnetic radiation) and leaf nitrogen (N) content for carbon assimilation. Radiation use efficiency (RUE) is an essential factor utilized by many of the simpler plant growing models to simulate the process of photosynthesis, i.e., conversion of light energy and carbon dioxide (CO2) to plant biomass. The productivity of crop is limited by its thermodynamic properties and the sustained climate of both the plant and its ecosystem. The application of industrial N fertilizers in agricultural production has enhanced the crop yield two to three times more in the last century to meet the rising worldwide population demands. This chapter is focused on the efficient use of solar radiations and integrated N management to enhance crop nitrogen production, taking into account soils, increased utilization of fertilizer, and better crop management strategies. Therefore, optimizing the efficiency of radiations and nitrogen use in agricultural systems is critical and yet to be explored.

Nanotechnology is an interdisciplinary stream of science which deals with the synthesis and application of nanoparticles (NPs) ranging from 1 to 100 nm. Nanotechnology is seen as a new tool for the various problems faced in agriculture and other allied sectors. Agriculture system is facing problems like generation of resistance among microbes due to excessive use of pesticides and deteriorating soil health by the abundant use of fertilizers, exhibiting damaging effect on the environment. A large quantum of applied fertilizers and pesticides get lost in the surrounding and not consumed by plants which limit the use of conventional methods. Nanoscience could be the potential solution to these limitations because bioactive compounds are encapsulated here and release at a controlled rate, providing input use efficiency. Diseases could be easily detected by the use of nanosensors at an early stage and thus also be controlled at the earliest for better productivity. Various disease controlling products are in use, such as nano-pesticides, nano-fungicides and nano-bactericides, to protect the crops from various kinds of biological stresses caused by different microorganisms. Small surface area to volume ratio of NPs contributes to their better absorption ability. Post-harvest techniques using nanosensors help check food quality with better packaging and transport which results in reduced post-harvest losses. The agriculture sector also contributes to a large amount of agriculture waste which is being transformed using nanomaterials and put into efficient use. Productivity in agriculture has been improved using nanobiotechnology by the use of nanocarriers to transfer the DNA (deoxyribonucleic acid) fragment at the proper site and to bring the desired result. Thus, nanomaterials contribute to improved nutrients use efficiency. This chapter entails the use of nanomaterials in improving soil health, plant productivity, disease detection, control and treatment, genetic transformation, post-harvest value addition, and reducing agriculture waste. Along with these benefits, nanomaterials may cause harm to the environment, so proper hazard assessment and regulations should be brought in for the optimal use of nanotechnology. Use of nanomaterials can result in the achievement of sustainable agriculture, thus, could be promoted with proper regulation in place.

Dairy farm releases large volume of wastewater which contains medium to high strength pollutants in the form of BOD, COD, phosphorous, ammonia, nitrogen, etc. Mostly these wastewaters are discharged into environment leading to environmental pollution. There are various wastewater treatment techniques, but most of these cannot be easily afforded by dairy farmers due to high installation and maintenance costs. This research work mainly focuses on treatment of dairy farm effluent using simple, cost-effective, and decentralized ‘Constructed wetland technology’. In this study, three vertical flow systems filled with 20 mm gravels were used with recirculation arrangement of 25%, 50%, and 75%. Results showed remarkable decrease in the average concentrations of all the pollutants. This paper discusses the performance and efficiency of VFCW system for removal of pollutants from dairy wastewater and also proposes the use of 20 mm gravels as an alternative treatment mechanism.