Urea fertilizer as a nitrogen source is used widely and globally. However, N loss through ammonia volatilization from applied urea has become a major drawback to agriculture. A pot experiment was conducted to determine the effect of rice straw biochar on (1) total N, soil exchangeable NH₄⁺, and available NO₃⁻ (2) uptake of N, P, and K in rice plants. The treatments evaluated were: (S: Soil only, U: soil + 175 kg ha⁻¹ urea, B1: soil + 175 kg ha⁻¹ urea + 5 t ha⁻¹ rice straw biochar, B2: soil + 175 kg ha⁻¹ urea + 10 t ha⁻¹ rice straw biochar, CB1: 50% soil + 50% commercial biochar potting media and CB2: 100% commercial biochar potting media). The addition of rice straw biochar at 5–10 t ha⁻¹ in the pot experiment significantly increased the soil total N availability by 33.33–46.67%. Treatments B1 and B2 also had significantly increased exchangeable NH₄⁺, NO₃⁻, P, and K in the soil over U. The soil availability nutrients increment in soil was attributed to the higher adsorption capacity of the rice straw biochar. Increment in soil nutrient availability such as N, P, and K increased the plant height, tiller number, greenness, and panicle number because of effective rice plant absorption. This resulted in dry matter production increment in line with plant nutrient uptake and use efficiency. Rice straw biochar at 5–10 t ha⁻¹ can improve the productivity of rice plants by increasing N retention in soil.

Nitrogen deficiency frequently occurs at agricultural soil because of NH₃ volatilization to the environment which results in low urea-N use efficiency by rice plants. A pot experiment was conducted to assess the synergistic effects of a mixture of rice straw and rice husk biochars (RSRH) on (1) total N, soil exchangeable NH₄⁺, and available NO₃⁻, and (2) uptake of N, P, and K in rice plant. RSRH biochar at 5 and 10 t ha⁻¹ had significantly minimized ammonia volatilization by 33.5% and 40.7%. Further, RSRH biochars also had significantly increased available NH₄⁺, NO₃⁻, available P, and available K in the soil over T1. In line to increase in soil nutrient availability, the rice plant height, tiller number, greenness, and panicle number were increased. This resulted in an increase of nutrient uptake, use efficiency, and dry matter production of the rice plant. RSRH biochar altered the soil environment by minimizing NH₃ loss and increasing soil nutrients for efficient plant uptake.

Rapid ammonia volatilization from surface applied urea in waterlogged condition is one of the drawbacks as it leads to poor nitrogen use efficiency by plants. Thus, a laboratory scale closed dynamic air flow system was carried out in this study to assess the effect of rice husk biochar on ammonia volatilization, soil exchangeable ammonium and available nitrate in comparison to the urea without additives under waterlogged conditions. The study conducted consists of 6 treatments, soil alone (T0), soil + 175 kg ha^-1 urea (T1), soil + 175 kg ha^-1 urea + 5 t ha^-1 rice husk biochar (T2), soil + 175 kg ha^-1 urea + 10 t ha^-1 rice husk biochar (T3), soil + 175 kg ha^-1 urea + 15 t ha^-1 rice husk biochar (T4) and soil + 175 kg ha^-1 urea + 20 t ha^-1 rice husk biochar (T5). T2, T3, T4, and T5 significantly minimized ammonia volatilization by 23.8%–34.5% compared to T1. However, only T2, T3, and T4 had significantly retained more soil exchangeable ammonium by 14%–43% compared to urea without biochar (T1). Additionally, soil available nitrate was lower in all treatments except T1. This clearly gives an idea that rice husk biochar minimize ammonia volatilization, retaining more ammonium and slowing down the conversion of ammonium to nitrate under waterlogged environment. Mixing urea with rice husk biochar at rate of 5 t ha^-1 and 10 t ha^-1 offers a significant advantage over urea alone. The mixture successfully increased formation of ammonium ions in soil over ammonia. Additionally, it has retained more ammonium and nitrate ions in the soil. Hence, biochar amended soil with urea is a promising approach to minimize ammonia loss and increase plant N use efficiency and uptakes.

Ammonia volatilisation causes major nitrogen losses from the soil and applied urea which results in low urea-N usage efficiency. Incubation experiment and pot experiment were conducted to assess the effect of enriched rice straw biochar on ammonia volatilisation, soil pH, exchangeable ammonium, available nitrate, and rice plant growth in comparison to the urea without additives under waterlogged conditions. During the incubation study, urea was amended with different rates of enriched rice straw biochar (5, 10, 15, and 20 t ·ha^-1). Urea amended with biochar at 5 to 10 t·ha^-1 had successfully minimized ammonia loss compared to urea without biochar. Besides, application rate of 5 to 10 t·ha^-1 of biochar also preserved more ammonium ions (65.37% and 66.54%, respectively), while at the same time, the retention of nitrate ions was 50.9% and 45.3% over urea without biochar. Similarly, 5 to 10 t·ha^-1 of enriched rice straw biochar increased soil N level and improved rice plant growth significantly in pot experiment. Precisely, incorporation of enriched rice straw biochar at rate of 5 and 10 t·ha^-1 offers wide variety benefits to soil amendments and rice plant nutrient uptake. Hence, the findings suggest that urea amended with enriched rice straw biochar altered the nutrients level in soil by improving rice plant growth.

Superfoods have captivated global attention with claims of enhanced health benefits beyond basic nutrition. This chapter examines their journey from traditional remedies to marketing phenomena, analyzing both scientific evidence and cultural significance. While rich in bioactive compounds like antioxidants and polyphenols that show promise for disease prevention and microbiome health, many superfood claims lack rigorous scientific validation. The research reveals that traditional healthy foods often provide comparable benefits at lower costs, highlighting accessibility issues.