Composting Constraints and Prospects in Bangladesh: A Review

Composting is a suitable environment-friendly technique to modify organic waste to organic fertilizers and works as soil conditioners by regulating different biological processes. The main objective of a sustainable agricultural production system can be achieved by using quality compost and thereby improving soil health and increased crop yield. This desktop research summarizes the role of composting for sustainable agricultural development with their prospective role, opportunities, and challenges in the context of Bangladesh. Some attention is also given to the composting process and compost industries in Bangladesh. Benefits and constraints regarding the use of compost for achieving sustainable agricultural production systems are also discussed.

Antioxidant Defense Mechanisms of Salinity Tolerance in Rice Genotypes

In order to elucidate the role of antioxidant responses in salinity tolerance in rice genotypes under salt stress, experiments were conducted using four rice varieties, including salt-sensitive BRRI dhan 28 and three salt-tolerant varieties BRRI dhan 47, BINA dhan 8 and BINA dhan 10. Thirty-day-old rice seedlings were transplanted into pots. At the active tillering stage(35 d after transplanting), plants were exposed to different salinity levels(0, 20, 40 and 60 mmol/L NaCl). Salt stress caused a significant reduction in growth for all the rice genotypes. Growth reduction was higher in the salt-sensitive genotype than in the salt-tolerant ones, and BINA dhan 10 showed higher salt tolerance in all measured physiological parameters. The reduction in shoot and root biomass was found to be minimal in BINA dhan 10. Chlorophyll content significantly decreased under salt stress except for BINA dhan 10. Proline content significantly increased in salt-tolerant rice genotypes with increased salt concentration, and the highest proline content was obtained from BINA dhan 10 under salt stress. Catalase and ascorbate peroxidase activities significantly decreased in salt-sensitive genotype whereas significantly increased in salt-tolerant ones with increasing salt concentration. However, salt stress significantly decreased guaiacol peroxidase activity in all the rice genotypes irrespective of salt tolerance. K^+/Na^+ ratio also significantly decreased in shoots and roots of all the rice genotypes. The salt-tolerant genotype BINA dhan 10 maintained higher levels of chlorophyll and proline contents as well as catalase and ascorbate peroxidase activities under salt stress, thus, this might be the underlying mechanism for salt tolerance.

A Review on Plant Responses to Soil Salinity and Amelioration Strategies

Soil salinity is a major abiotic stress, limiting plant growth and development worldwide. Plants grown under saline soil condition experiences a significant amount of high osmotic stress, ion toxicities and nutritional disorder, and these are responsible for poor soil physical condition as well as lead to reduced plant productivity. Plants exhibit a number of responses under salt stress by affecting morphological, physiological and biochemical process. A complete understanding of how plants respond to soil salinity and comprehensive management approaches of combining physiological and biochemical attributes with molecular tools are essential for mitigating the adverse effects of salinity on plant growth and productivity. Recent reports on the plant responses due to soil salinity highlighted the importance of integration of different advanced strategies to address the problem of soil salinity. This review will focus on morphological and physiological changes of plants under saline soil and an overview of suitable strategies to regulate plant adaptation and tolerance to salinity stress.

Analysis of existing agroforestry practices in Madhupur Sal forest: an assessment based on ecological and economic perspectives

A study was conducted in Madhupur sal forest of Tangail, Bangladesh to identify the suitable agroforestry practices of the area. Considering the ecological aspects of different agroforestry practices 10 sample plots （10 m× 10 m） from each land uses were taken, including natural forest to get a comparative scenario. The study showed that among the different agroforestry practices, Margalef and Shannon- Weiner index values are the maximum for pineapple agroforestry and lower for banana agroforestry, and Evenness index value is the maximum for lemon agroforestry. Determination of tree biomass in different land uses revealed that it is highest （3 078.6 kg/100 m^2） in natural forest followed by pineapple agroforestry, lemon agroforestry and banana agroforestry. Soil pH, moisture content, organic matter, organic carbon, phosphorus and total nitrogen showed statistically significant variation while bulk density, particle density, sulphur and potassium did not show any statistically significant variation among the land uses. Soil fertility status showed that pineapple agroforestry is more fertile than rest of other land uses. The Net Present Value （NPV） indicated that banana agroforestry is financially more profitable than other two systems, while the Benefit- Cost ratio （BCR） is higher in pineapple agroforestry （4.21 in participatory agroforestry and 3.35 in privately managed land）. Even though banana agroforestry gives higher NPV, capital required for this practice is much higher. The findings suggest that pineapple agroforestry has a tendency towards becoming ecologically and economically more sound than other two practices as it has better ecological attributes and required comparatively low investment.

Climate Change and Its Adverse Impacts on Plant Growth in South Asia:Current Status and Upcoming Challenges

Socioeconomic development,adaptive capacity of the population,and demographic conditions across the states of South Asia make it more vulnerable to climate change.South Asia is daily going to be more vulnerable to climate change and climatic variability.This region is facing multiple challenges in terms of climate change,dilapidation of ecosystems,and food insecurity.Climate is the primary determining factor for agricultural output,which unswervingly influences food production across the globe.South Asia is mainly an agricultural foundation based region and thus the economy of these regions directly depends on agriculture and agricultural production.Due to the extensive dependence on natural assets for thriving,it makes the people of this region more vulnerable to climate change.This region is now under serious risk from sea-level rising and growing incidences of extreme events such as flash floods,enhanced temperature,drought,salinity,cyclones,storms,landslides,and irregularity of precipitation.These abiotic stresses continuously disturb plant growth and productivity.It is now the time to take urgent action on these issues towards a sustainable,inclusive and resource efficient way to overcome this.In this review,we summarize the overall situation of climate change in the South Asian countries and their adverse consequences on plants,and upcoming challenges towards a sustainable production.

Applying organic amendment enriches nutrient status of municipal solid waste compost and its application enhances tuber yield and nutrient concentrations of potato

Elevated price of chemical fertilizers and poor nutrient content in conventional organic sources such as municipal solid waste(MSW)compost necessitate the production of nutrient enriched compost which could serve as a potential alternative organic fertilizer option.We studied three types of amended compost that were prepared by mixing 20%mustard oil cake(MOC)and 30%poultry manure(PM)or cow dung or sugarcane press mud(SPM)with 50%MSW compost.Trichoderma viride was inoculated into every type of compost.The rate of amended or unamended MSW compost application was 10 t ha^(−1).The use of different amendments improved the nutrient level of MSW compost,of which the N increment was remarkable,ranging from 1.14%N(unamended compost)to 2.9%–3.22%N depending on the types of amendment.A field experiment was conducted to evaluate performances of the amended MSW composts on the yield and nutrient content of potato(variety BARI Alu25).All compost treatments except the sole MSW compost treatment produced significantly higher tuber yields than the sole fertilizer treatment.The press mud based MSW compost+fertilizer treatment produced the highest tuber yield of 31.6 t ha^(−1)(65%increase over 100%fertilizers and 57%increase over 100%compost treatment).The tuber N concentration varied from 0.128%to 0.594%,P from 0.018%to 0.035%,K from 0.213%to 0.313%and S from 0.020%to 0.053%,with the highest result recorded with press mud+fertilizer treatment.The use of amended composts had residual effects on soil N,P,K and S contents.Thus,the treatment containing 50%fertilizer+50%compost mixture(MSW:MOC:SPM in a ratio of 5:2:3)performed the best followed by PM amended compost.It is concluded that integrated use of 10 t ha^(−1) organic amended MSW compost with chemical fertilizers can ensure higher crop yield,nutrient content and sustained soil fertility in nutrient-deficient sub-tropical soil.