Highly active biostimulant Paecilomyces variotii extracts reduced controlled-release urea application while maintaining rice yield.

BACKGROUND: The high cost of controlled-release urea (CRU) has prompted this study to explore whether the amount of CRU can be reduced by adding biostimulants while maintaining or increasing rice yield. A 2 year field experiment was conducted with CRU at three levels (60%, 80%, and 100% of the recommended nitrogen (N) fertilizer) and a novel biostimulant Paecilomyces variotii extract (ZNC), to investigate their synergistic effects on yield, nitrogen use efficiency (NUE), and net profitability of rice. RESULTS: Controlled-release urea achieved a significantly higher gain yield and NUE than conventional urea with the same N level, which could be attributed to its N supply. Even if the N level of CRU was reduced by 40%, both rice yield and net profit were still significantly higher than for the full amount of urea. Paecilomyces variotii extract sprayed on the surface of CRU at a dose of only 87.5 mL ha-1 exhibited ultra-high effectiveness by increasing the panicles, the N accumulation, and the rice yield. Controlled-release urea enriched by ZNC achieved significantly higher gain yield than CRU alone, increasing the yield by 9.2% and 8.7%, respectively, in 2 years under the full recommended N rate. The combination of 80% CRU and ZNC showed no significant difference in rice yield from treatment with 100% CRU, indicating that the rate of CRU could be reduced by ZNC. The application of ZNC further increased NUE, N partial factor productivity, and net profit. CONCLUSION: The CRU and ZNC combination provided a feasible approach for reducing N input while maintaining rice yield and agricultural sustainability. © 2021 Society of Chemical Industry.

Paecilomyces variotii Extracts and Controlled-Release Urea Synergistically Increased Nitrogen Use Efficiency and Rice Yield.

A novel biostimulant, Paecilomyces variotii extracts (ZNC), with the ability to promote N absorption in the plant at a very low level has been proved in the lab experiment, but its chemical composition and practical effect in the field remain unclear. In this work, we determined the molecular composition of ZNC. Then, a three-year field experiment was conducted to investigate the synergistic effects of controlled-release urea (CRU) without ZNC or with ZNC at three doses (87.5, 175, and 262.5 mL ha-1) on the yield, nitrogen use efficiency (NUE), and net returns of rice. Results indicated that ZNC contained more carbohydrates, amino acids, alkyl structures, and less aromatic structures with a molecular weight between 140 and 2507 Da. Rice yield was 6.9-21.0% higher with CRU than with conventional urea. Combining CRU with ZNC at a dose of 87.5 mL ha-1 performed the best and significantly increased rice yields by 8.7-12.1%, NUE by 15.0-20.2%, and average net returns by 10.9-15.4% during three rice-growing seasons compared to the application of CRU only, which is attributed to the positively increasing panicles and N uptake of rice. With the increased dose of ZNC, the yield of rice showed a decreasing trend, but the yield was still higher/not significant than the CFF treatment without ZNC. Therefore, the planting patterns with the combination of CRU and biostimulant are an efficient way to increase the rice grain yield and net returns.

Developing water and nitrogen budgets of a wheat-maize rotation system using auto-weighing lysimeters: Effects of blended application of controlled-release and un-coated urea.

Evaluation of the effectiveness of best management practices for reducing nitrate leaching in agricultural systems requires detailed water and nitrogen (N) budgets. A 3-year field experiment using 15 auto-weighing lysimeters was set up to quantify nitrate leaching, crop evapotranspiration (ET), and N and water use efficiencies within an intensive wheat-maize rotation system in the Northern China Plain. The lysimeter consists mainly of the following: (1) high-resolution weighing cells; (2) ceramic solution samplers for soil solutions collection; and (3) circular stainless steel leaching trays for collecting seepage water. Two N fertilizer types were applied at two rates (150 and 225 kg N hm-2 for each crop) with no-N applied as the control. The N fertilizer types were monotypic un-coated urea and a blend product with controlled-release urea (CRU) and un-coated urea. The results indicate that when compared with un-coated urea at the same application rate, the blend product greatly improved water and N use efficiencies with significant increase in yields and crop ET as well as reduction of nitrate accumulation and leaching in the soil profile (p < 0.05). This was mostly because the blend product consistently supplied N to meet crop demands over the entire growth season. The study implied that effective best management practices to control nitrate leaching should be based on technically sound fertilization and irrigation schemes in terms of timing, rate, and fertilizer type to suit site specific conditions.

Seaweed Extract Improved Yields, Leaf Photosynthesis, Ripening Time, and Net Returns of Tomato (Solanum lycopersicum Mill.).

Overuse of chemical fertilizers in the intensive greenhouse tomato cultivation system has limited the increase of plant production. Nowadays, seaweed extract has been gradually applied in agriculture as an effective way to achieve a higher yield of crops, but its effects on tomato cultivation have not been fully explored. In this study, a greenhouse experiment was conducted in Shandong province of China with a novel seaweed extract (SES) originated from Sargassum horneri, to investigate the effects of different doses of SES (0, 30, 60, and 90 kg hm-2) on yields, quality, ripening time, and net returns of tomato. The results indicated that the application of SES significantly increased tomato yield by 4.6-6.9% compared to the control, which is attributed to the improved photosynthetic capacity of tomato leaves. The yields of tomato increased first and then decreased with increasing dosage of SES, and SES applied at the dose of 60 kg hm-2 achieved the highest tomato yield. Compared to the control, SES at 60 and 90 kg hm-2 significantly increased the hardness of tomato by 10.2 and 19.8%, respectively, and this can help to reduce losses during transportation and storage. Moreover, SES shortened the ripening time of tomato, and the coincidence between tomato harvest and sale price peak achieved a high net return.

Biochar derived from corn straw affected availability and distribution of soil nutrients and cotton yield.

Biochar application as a soil amendment has been proposed as a strategy to improve soil fertility and increase crop yields. However, the effects of successive biochar applications on cotton yields and nutrient distribution in soil are not well documented. A three-year field study was conducted to investigate the effects of successive biochar applications at different rates on cotton yield and on the soil nutrient distribution in the 0-100 cm soil profile. Biochar was applied at 0, 5, 10, and 20 t ha-1 (expressed as Control, BC5, BC10, and BC20, respectively) for each cotton season, with identical doses of chemical fertilizers. Biochar enhanced the cotton lint yield by 8.0-15.8%, 9.3-13.9%, and 9.2-21.9% in 2013, 2014, and 2015, respectively, and high levels of biochar application achieved high cotton yields each year. Leaching of soil nitrate was reduced, while the pH values, soil organic carbon, total nitrogen (N), and available K content of the 0-20 cm soil layer were increased in 2014 and 2015. However, the changes in the soil available P content were less substantial. This study suggests that successive biochar amendments have the potential to enhance cotton productivity and soil fertility while reducing nitrate leaching.

Effects of readily dispersible colloid on adsorption and transport of Zn, Cu, and Pb in soils.

Soil colloids (<0.002 mm) were extracted from three types of soils to make the colloid-bound forms of Zn, Cu, and Pb solution. The clay mineral types and composition of the colloids, the adsorption characteristics of the colloids, and the effect of readily dispersible colloid on the transport of metals and the quality of the soils and groundwater were studied. The results showed that the adsorption capacity of Cu, Zn, and Pb was greater for the Aquic Vertisols (Shajiang Black soil) as compared to the Udic Luvisols (Brown soil) and Usdic Luvisols (Cinnamon soil), due to the difference of clay content and clay mineral composition in the different soils. The adsorption capacity of Pb was much higher than that of Zn and Cu for the same soils, which would contribute to the chemical properties of metals and specific adsorption characters of the colloids. The mobility of Zn in soils was greater than that of Cu and Pb, while similar trend was found in the transportation processes for Zn and Cu. The concentration of Zn and Cu in leachates increased as the leaching solution volume increased, but the migration of Pb was negligible, and the concentration of Pb could not been detected in leachates even after 7.5 pore volume leaching solution. The influence of mobility on Zn and Cu transport was different for different type of colloids. The mobility caused by readily dispersible colloids from Aquic Vertisols was greater as compared to that of Udic Luvisols and Usdic Luvisols. Analysis of soils after column leaching indicated that Zn was distributed much deeper than Cu, but Pb was almost not migrated, and mainly accumulated in the soil surface. Therefore, Zn had greater tendency for the groundwater pollution than Cu and Pb, and Pb tends to contaminate the surface soils.