Reducing nitrogen leaching using wood vinegar treated in urea-fertilized soil.

Wood vinegar (WV) is known to retard the release of ammonium (NH4+) from urea by inhibiting urea hydrolysis. However, the effect of WV on nitrogen leaching in soil is not known, and there are few studies on the effect of WV on microbial activity although WV exhibits antibacterial properties against pathogens in agriculture. Therefore, the purpose of this study was to investigate the effect of WV on controlling nitrogen leaching and soil microbial activity. Soils were treated with urea and WV, and the available inorganic nitrogen concentrations in the soil were compared with those from soils treated with N-(n-butyl)thiophosphoric triamide (NBPT), a commonly used urease inhibitor. The nitrate concentration in the soil was significantly decreased in the WV treatment, although the ammonium concentration was not affected by the WV treatment. Basal soil respiration was significantly increased in the WV and NBPT treatments although the microbial biomass was increased in the urea only treatment. The ammonium nitrogen concentration in the leachate was not significantly different in the WV and urea-treated soil compared to the urea-only treatment. However, the nitrate leaching increased in the soil treated only with urea at 16 days after the treatment although there was no statistically significant difference in the total leached nitrate. Therefore, WV can be used to reduce nitrogen leaching and enhance soil microbial activity.

Effect of polypropylene microplastics on seed germination and nutrient uptake of tomato and cherry tomato plants.

Although microplastic (MP) pollution in farmland increased, the effect of MPs on plant growth was not clearly explained. Therefore, the object of the study was to evaluate the effect of polypropylene microplastics (PP-MPs) on plant germination, growth, and nutrient uptake under hydroponic conditions. The effect of PP-MPs on seed germination, shoot and root length, and nutrient uptake were assessed using tomato (Solanum lycopersicum L.) and cherry tomato (Solanum lycopersicum var. cerasiforme) seeds grown in half-strength Hoagland solution. The results showed that PP-MPs did not significantly affect seed germination, but positively affected the shoot and root elongation. In cherry tomato, the root elongation was significantly increased by 34%. Microplastics also affected nutrient uptake by plants, however, the effect varied depending on elements and plant species. The Cu concentration was substantially increased in tomato shoot while it decreased in cherry tomato root. Nitrogen uptake decreased in MP treated plants compared to the control and phosphorus uptake was significantly decreased in the shoot of cherry tomato. However, the root-to-shoot translocation rate of most macro nutrients decreased following exposure to PP-MPs indicating that long-term exposure to MPs may lead to a nutritional imbalance in plants.

Monitoring of plant-induced electrical signal of pepper plants (Capsicum annuum L.) according to urea fertilizer application.

Plant-induced electrical signals (PIES) can be non-destructively monitored by inserting electrodes into plant stems, which reflect plant nutrient and water uptake. The main objective of this study was to evaluate the growth of pepper plants with different urea applications (low fertilizer: N0, Control: N1, and high fertilizer: N2) in soil by monitoring PIES. The PIES value was found to be low in the low urea treatment group while the two times higher urea applied pepper had the highest PIES value. The nutritional content of the stem, leaves and soil did not correlate with PIES because of dilution effect by high biomass with high urea application, but principal component analysis showed that the PIES was positively associated with pepper biomass and soil EC. The high fertilizer did not affect chlorophyll and proline contents in pepper leaves. The assessment of plant growth by PIES has advantages because non-destructive, real time and remote monitoring is possible. Therefore, PIES monitoring of different plants grown under various cultivation environments is useful method to evaluate plant activity and growth.