The effect of soil applied zeolite, foliar application of selenium and silicon on the agronomic and physiologic traits of canola grown under salt stress conditions was investigated in two-year field experiment during 2012 and 2013. The experimental design was randomized complete blocks, arranged in factorial with 27 treatments forming combinations of zeolite (0, 5 and 10 ton ha⁻¹), selenium (0, 2 and 4 g liter⁻¹) and silicon (0, 2 and 4 g liter⁻¹) and three replicates. The results indicated that zeolite improved plant growth in terms of plant height and increased yield and yield components of canola. In addition, biological yield, harvest index and oil percentage increased due to zeolite application. Zeolite could decrease respiration, malondialdehyde and proline in salt-stressed plants. Soluble sugars and potassium content increased in response to zeolite application while sodium content significantly decreased. Selenium led to an increase in plant height, silique number, seed number in silique, biological yield, harvest index and oil percentage, while respiration, malondialdehyde, proline and sodium decreased on account of selenium application. Similarly, silicon had a significant effect on growth and agronomic traits and increased them. Silicon promoted chlorophyll synthesis while preventing malondialdehyde, proline and sodium accumulation in plant tissues. Catalase and superoxide dismutase activities were suppressed by using silicon on plants. Interaction between zeolite and selenium was significant on leaf relative water content, photosynthesis, chlorophyll content and activity of antioxidant enzymes. In addition, seed weight, seed yield, photosynthesis and soluble sugar content were affected by selenium and silicon application.

Biochar is known as a well-developed porous carbonaceous material with multifunctional abilities that can enhance the physical properties of soils. However, the lack of certainty about the consequences of biochar application to soils has limited its acceptability. Application of biochar can lead to a series of changes in the physical functions of soil, which are crucial in both agricultural and environmental management. The type of feedstock, pyrolysis conditions, size of particles, and rate of amendments are responsible for biochar effectiveness. Concurrently, the physical characteristics of soil, such as particle-size distribution, can intensify the impacts. Beside the physical attributes, the chemical components and interactions between biochar and the soil interface may play an important role. The chemical properties, such as the value of electrical conductivity, pH and zeta potential, are the remarkable parameters in the hydrophysical behavior. The summary proposes that biochar has a great contribution In enhancing the definite range of aggregation formation, reduction of compaction and shear strength frequency and/or intensity, improvement of microorganisms activity, and abundance. Simultaneously, biochar plays a devastating role by filling the pores, blocking the water flow pathways, and inhibiting macro fauna growth. Particle size of biochar as a major factor, and surface functional groups as a minor factor, affect the performance of biochar in improving the hydrophysical properties of amended soils. The increment in the dosage of biochar application is not promising to enhance the physical properties of soils. Therefore, it is necessary to find a balance between the consumption of biochar and promotion of the soil-water dynamic. This review provides an overview of fastidious perspectives on how to achieve an efficient and sustainable use of biochar in hydrophysical properties.

In the present study, integration of nitrogen (N) and zeolite on growth, photosynthesis, yield and yield components, nitrate reductase activity, and plant nutrient content on canola (Brassica napus L. cv. SLM₀₄₆) was evaluated during two growing seasons (2010 and 2011) at East Azerbaijan Research Center for Agriculture and Natural Resources, Tabriz, Iran. The experiment was conducted as a 4 × 5 factorial design with three replications. Different levels of zeolite (0, 4, 8, and 12 ton ha⁻¹) and nitrogen (N; 0, 150, 200, 250, and 300 kg ha⁻¹) were added and mixed with soil thoroughly. According to combined analysis of variance, effect of year was significant only on silique number per plant, respiration rate, and iron (Fe) content. Also results indicated that N fertilizer increased plant height, silique number per plant, seed number per silique, 1000-seed weight, and finally seed yield. Similarly, zeolite increased yield and yield components whereas plant height was not affected by zeolite in the second year. Oil yield decreased due to N and zeolite application. In addition, photosynthesis and respiration improved on account of N and zeolite treatments. Nitrate reductase activity significantly was promoted by N and zeolite. Furthermore, micro- and macroelements were affected by N or zeolite application, so that N and zeolite decreased P content whereas N increased N, K, Fe, and zinc. In general our results demonstrated that zeolite application can increase canola growth and production, which may be through increasing N-use efficiency and improving soil physical characteristics.

Considering the importance of onion and its cultivation in saline soils, a two-year experiment was carried out to investigate the effects of soil applied zeolite and foliar application of selenium (Se) and silicon (Si) on onion yield, qualitative traits and physiological attributes, under salinity stress. An experiment was performed at three-way factorial design with three replications as follows: zeolite at three levels (0, 4 and 8 ton ha-1), Se at three levels (0, 0.5 and 1 kg ha-1) and Si at three levels (0, 200 and 400 kg ha-1). The results indicated that the effect of year was significant on all studied traits except for soluble solids, bulb nitrogen, leaf sodium and potassium, chlorophyll content and peroxidase activity. Number of small-sized bulbs decreased with increasing zeolite, Se and Si application. Dry matter, soluble solids, nitrogen content, nitrate concentration as well as protein content significantly increased due to zeolite, Se and Si application. Leaf sodium content and enzyme activity decreased due to zeolite, Se and Si application. Overall, 8 ton ha-1 zeolite along with 1 kg ha-1 Se and 400 kg ha-1 Si caused the maximum onion yield and qualitative and physiologic traits including soluble solids, potassium, protein, chlorophyll and photosynthesis .