Appropriate foliar application of zinc (Zn) and zinc oxide nanoparticles (ZnO-NPs) is important for the proper growth and yield of tomato. However, the effects of foliar application of Zn and ZnO-NPs were not well-studied on tomato production. A pot experiment was conducted at glasshouse (8D) conditions under the Faculty of Agriculture, Universiti Putra Malaysia (UPM) to evaluate the effectiveness of Zn and ZnO-NPs on growth, yield, nutrient uptake, and fruit quality of tomatoes and to compare between the Zn nutrient and ZnO-NPs. Treatment combinations were 14 viz. T₁ = 0 (control), T₂ = 1500 ppm (mg/L) Zn nutrient, T₃ = 2000 ppm (mg/L) Zn nutrient, T₄ = 2500 ppm (mg/L) Zn nutrient, T₅ = 75 ppm ZnO nanoparticle, T₆ = 100 ppm ZnO nanoparticle, and T₇ = 125 ppm ZnO nanoparticle along with two tomato varieties. The experimental design was a split plot with four replications. Results indicated that foliar application of 100 ppm ZnO-NPs performed best in terms of growth parameters, physiological traits, yield attributes, yield, and quality traits of tomatoes. The same treatment (100 ppm ZnO-NPs) contributed to attain the highest nutrient uptake. Recovery use efficiency of Zn was highest with foliar application of 75 ppm ZnO-NPs. The highest yield increment (200%) over control was from foliar sprayed with 100 ppm ZnO-NPs. Comparing the two varieties, MARDI Tomato-3 (MT3) showed better than MARDI Tomato-1 (MT1). As is appears from the results, foliar application of zinc oxide nanoparticles was more efficient than conventional zinc fertilizer. Therefore, the foliar sprayed with 100 ppm ZnO-NPs can be suggested to improve quantity and quality of tomato in glasshouse soil conditions.

Soil acidity is a major problem of agriculture in many parts of the world. Soil acidity causes multiple problems such as nutrient deficiency, elemental toxicity and adverse effects on biological characteristics of soil, resulting in decreased crop yields and productivity. Although a number of conventional strategies including liming and use of organic and inorganic fertilizers are suggested for managing soil acidity but cost-effective and sustainable amendments are not available to address this problem. Currently, there is increasing interest in using biochar, a form of biomass derived pyrogenic carbon, for managing acidity while improving soil health and fertility. However, biochar varies in properties due to the use of wide diversity of biomass, variable production conditions and, therefore, its application to different soils can result in positive, neutral and or negative effects requiring an in-depth understanding of biochar-acid soil interactions to achieve the best possible outcomes. Here, we present a comprehensive synthesis of the current literature on soil acidity management using biochar. Synthesis of literature showed that biochars, enriched with minerals (i.e., usually produced at higher temperatures), are the most effective at increasing soil pH, basic cation retention and promoting plant growth and yield. Moreover, the mechanism of soil acidity amelioration with biochar amendments varies biochar types, i.e., high temperature biochars with liming effects and low temperature biochars with proton consumption on their functional groups. We also provide the mechanistic interactions between biochar, plant and soils. Altogether, this comprehensive review will provide guidelines to agricultural practitioners on the selection of suitable biochar for the reclamation of soil acidity.

Growing vegetables can be seen as a means of improving people’s livelihoods and nutritional status. Tomatoes are one of the world’s most commonly planted vegetable crops. The nutritional arrangement of the tomato depends on the quantity and type of nutrients taken from the growing medium, such assoil and foliar application; therefore, an adequate amount of macro- and micro-nutrients, including zinc (Zn) and zinc oxide nanoparticles (ZnO-NPs), are crucial for tomato production. Zinc foliar spraying is one of the effective procedures that may improve crop quality and yield. Zinc oxide nanoparticles (ZnO-NPs) are represented as a biosafety concern for biological materials. Foliar application of Zn showed better results in increasing soluble solids(TSS), firmness, titratable acidity, chlorophyll-a, chlorophyll-b, ascorbic acid, amount of lycopene. Researchers have observed the effect of nanoparticles of zinc oxide on various crops, including tomatoes. Foliar spraying of ZnO-NPs gave the most influential results in terms of best planting parameters, namely plant height, early flowering, fruit yields as well as lycopene content. Therefore, more attention should be given to improving quantity and quality as well as nutrient use efficiency of Zn and ZnO-NPs in tomato production. Recent information on the effect of zinc nutrient foliar spraying and ZnO-NPs as a nano fertilizer on tomato productivity is reviewed in this article.

A pot experiment was executed to investigate the impact of biochar and compost with water-saving irrigation on the rice yield, water use efficiency, and physicochemical properties of soil. Two irrigation regimes—namely alternate wetting and drying (AWD) and continuous flooding (CF)—and four types of organic amendments (OA)—namely rice husk biochar (RHB), oil palm empty fruit bunch biochar (EFBB), compost and a control—were applied to evaluate their effects. Under the AWD irrigation regime, the maximum grain was produced by RHB (241.12 g), whereas under the same organic amendments, both AWD and CF produced a similar grain yield. Under the same organic amendment, a significantly higher water use efficiency (WUE) was observed from the AWD irrigation with RHB (6.30 g L⁻¹) and EFBB (5.80 g L⁻¹). Within the same irrigation regime, soil pH, cation exchange capacity, total carbon, total nitrogen and available phosphorus were enhanced due to the incorporation of biochar and compost, while higher soil exchangeable potassium was observed under CF irrigation for all treatments. RHB and EFBB significantly reduced the soil bulk density (up to 20.70%) and increased porosity (up to 16.70%) under both irrigation regimes. The results imply that the use of biochar with AWD irrigation could enhance the nutrient uptake and physicochemical properties of soil and allow rice to produce a greater yield with less water consumption.

Over half of the world’s population depends on rice for its calorie supply, although it consumes the highest amount of water compared to other major crops. To minimize this excess water usage, alternate wetting and drying (AWD) irrigation practice is considered as an efficient technique in which soil intermittently dried during the growing period of rice by maintaining yield compared to a flooded system. Continuous AWD may result in poor soil health caused by carbon loss, nutrient depletion, cracking, and affecting soil physical properties. Due to being a potential organic amendment, biochar has a great scope to overcome these problems by improving soil’s physicochemical properties. Biochar is a carbon enriched highly porous material and characterized by several functional groups on its large surface area and full of nutrients. However, biochar’s implication for sustaining soil physicochemical and water retention properties in the AWD irrigation systems has not been widely discussed. This paper reviews the adverse impacts of AWD irrigation on soil structure and C, N depletion; the potential of biochar to mitigate this problem and recovering soil productivity; its influence on improving soil physical properties and moisture retention; and the scope of future study. This review opined that biochar efficiently retains nutrients and supplies as a slow-release fertilizer, which may restrict preferential nutrient loss through soil cracks under AWD. It also improves soil’s physical properties, slows cracking during drying cycles, and enhances water retention by storing moisture within its internal pores. However, long-term field studies are scarce; additionally, economic evaluation is required to confirm the extent of biochar impact.

Biochar, an ecologically friendly soil amendment, is suggested for large-scale field application for its multiple potential benefits, including carbon sequestration, crop yield improvement, and the abatement of greenhouse gas emissions. However, it is unknown how effective it is in changing soil properties and its associated yield improvement when biochar is co-applied with lime in acidic soil. Here, we examined the effects of two different biochars, i.e., rice husk biochar (RHB) and oil palm empty fruit bunches biochar (EFBB), and lime on nutrient availability, the yield of maize, and soil CO₂ emission of acid soil. Biochars were applied at two different rates (10 and 15 t ha⁻¹) in combination with two rates of lime (100% and 75%), while the recommended rate of NPK fertilizers, 100% lime, and without any amendments (control) were also included. Hybrid sweet corn was grown in pots with 20 kg soils for 75 days. Plant performance and soil analyses were performed before and after crop maize cultivation while CO₂ emission was recorded. Compared to the control, combined RHB biochars with lime significantly buffered soil pH and increased nutrient availability (e.g., P by 137%), while reducing Al and Fe concentration at harvest. These changes in soil properties significantly increased maize yield (by 77.59%) and nutrient uptake compared to the control. Between the two biochars, RHB was relatively more effective in making these changes than EFBB. However, this treatment contributed to a greater carbon loss as CO₂ (209% and 145% higher with RHB and EFBB) from soil than the control. We believe that biochar-mediated buffering of soil pH is responsible for this change. Our results suggest that combined biochar application could bring desirable changes in soil properties and increase crop performance, although these effects can be short-lived.