Combining Organic Fertilizer With Controlled-Release Urea to Reduce Nitrogen Leaching and Promote Wheat Yields

Soil deterioration, low nitrogen use efficiency (NUE), and environmental risks caused by excessive chemical N fertilizer use are key factors restricting sustainable agriculture. It is extremely critical to develop effective N management strategies that consider both environmental and agronomic benefits. From 2017 to 2019, a field experiment was conducted to assess the effects of combinations of organic fertilizers (OF, provided at 30, 50, and 70% of the total applied N) and controlled-release urea (CU) on the NUE, N leaching and wheat yield compared with the effects of urea and CU. The results suggested that OF released N slowly in the early stage and showed a significant residual effect, while CU released N quickly in the first 2 months. The OF substitutes with 30–50% CU increased wheat yield by 4.2–9.2%, while the 70%OF+30%CU treatment showed no significant difference relative to the urea treatment. The average maximum apparent NUE recovery (50.4%) was achieved under the 50%OF+50%CU treatment, but the partial factor productivity was not affected by the N type. As the OF application rate increased, the total carbon content increased, and the total N value decreased. The NO3−-N and NH4+-N concentrations in the OF+CU treatments were lower before the jointing stage but higher from the grain-filling to mature stages than those in the urea treatment. NO3−-N and NH4+-N were mainly concentrated in the 0–60-cm layer soil by OF substitution, and N leaching to the 60–100-cm soil layer was significantly reduced. Hence, the results suggest that the combination of 30–50% OF with CU synchronizes absorption with availability due to a period of increased N availability in soils and proved to be the best strategy for simultaneously increasing wheat production and reducing N leaching.

Influence of variable biochar concentration on yield-scaled nitrous oxide emissions, Wheat yield and nitrogen use efficiency

An important source of the destructive greenhouse gas, nitrous oxide (N2O) comes from the use of ammonium based nitrogen (N) fertilizers that release N2O in the incomplete conversion (nitrification) of NH4+ to NO3ˉ1. Biochar has been shown to decrease nitrification rates and N2O emission. However, there is little information from semi-arid environments such as in Pakistan where conditions favor N2O emissions. Therefore, the object was to conduct field experiment to determine the impact of biochar rates in the presence or absence of urea amended soils on yield-scaled N2O emissions, and wheat yield and N use efficiency (NUE). The experiment on wheat (Triticum aestivum L.), had a randomized complete block design with four replications and the treatments: control, sole urea (150 kg N ha−1), 5 Mg biochar ha−1 (B5), 10 Mg biochar ha−1 (B10), urea + B5 or urea + B10. In urea amended soils with B5 or B10 treatments, biochar reduced total N2O emissions by 27 and 35%, respectively, over the sole urea treatment. Urea + B5 or + B10 treatments had 34 and 46% lower levels, respectively, of yield scaled N2O over the sole urea treatment. The B5 and B10 treatments had 24–38%, 9–13%, 12–27% and 35–43%, respectively greater wheat above-ground biomass, grain yield, total N uptake, and NUE, over sole urea. The biochar treatments increased the retention of NH4+ which likely was an important mechanism for reducing N2O by limiting nitrification. These results indicate that amending soils with biochar has potential to mitigate N2O emissions in a semi-arid and at the same time increase wheat productivity.

Effects of Urea-Ammonium Nitrate Solution on Yield, N2O Emission, and Nitrogen Efficiency of Summer Maize Under Integration of Water and Fertilizer

In order to clarify the effects of urea-ammonium nitrate solution (UAN) on the yield, nitrogen-use efficiency (NUE), and N2O emissions of summer maize under the condition of water and fertilizer integration, different types of nitrogen fertilizer were selected, namely, ordinary urea (urea) and UAN. Our results showed that the application of UAN was beneficial to improve the dry matter accumulation and the distribution of summer maize. Compared with urea treatment, the total nitrogen accumulation of UAN treatment was increased by 15.8%, and the harvest index was increased by 5.5%. The partial productivity, agronomic use efficiency, and recovery rate of nitrogen for UAN treatment were also increased by 9.1, 19.8, and 31.2%, respectively, compared to those of urea treatment. The soil nitrogen dependence rate treated with UAN was significantly decreased by 13.6%, compared to that of urea treatment. In addition, UAN was beneficial to reduce N2O emissions. The N2O warming potential (GWPN2O) and N2O greenhouse gas intensity (GHGIN2O) of urea treatment were 39.3 and 52.4% higher, compared to those of UAN treatment. The improvement of dry matter accumulation and distribution and nitrogen efficiency for UAN treatment were beneficial to increase the grain yield by 9.1%, compared to that of urea treatment. In conclusion, under the fertigation, the application of UAN favors higher yield and nitrogen uptake, with less soil nitrogen residue, higher NUE, and better environmental effect.

Application of Organic Fertilizer in Sidenuk Varieties to Reduce Using Urea

Sidenuk rice is a superior rice variety produced by BATAN through a radiation mutation technique. The new varieties that have been produced need to be supported by efforts to optimize production through fertilization technology. The purpose of this study was to determine the effect of organic fertilizer which can increase growth, production and reduce the use of urea fertilizer in lowland rice optimally. The study was conducted using a completely randomized design. Each was repeated 4 times so that the total experimental unit (pot) was 32 rice pots. The treatments include (1) Control (without urea fertilizer), (2) Control (+) 100% urea, (3) 50% urea, (4) Local microorganisms (MOL), (5) Compost, (6) Biochar , (7) Azolla, (8) Mol + Compost + Biochar + Azola + SP 36 and KCl. The results showed that the highest grain weight was found in the 100% urea treatment, which was 43.97 g plant-1. MKBA treatment (MOL fertilizer, compost, biochar, azolla) showed values that were not significantly different from 100% urea treatment. Organic fertilizer formula (MOL fertilizer, compost, biochar, azolla) can reduce the use of urea fertilizer by 50%.

Preliminary Observations On The Use Of Dry Urea Treatment And Toasting For Improving The Nutritive Value Of Jackbean

Raw unprocessed jackbean contains 28 - 30% crude protein but also contains toxic elements that limit its use as feed ingredient for monogastric animals. A 21-day feeding trial was conducted to determine the effect of dry urea treatment prior to toasting on its nutritive value for young broiler chicks. One of two batches of raw jackbean was mixed with 2.5% of its weight of crushed urea and allowed to stand for 10 days and then toasted. The other batch was toasted without urea application. The two treated jackbean meals were used to compound broiler starter diets at 10 and 20% dietary levels, respectively, and along with control diet fed to groups of 40 young broiler chicks for 21 days. Hydrolysis of urea by the urease of the jackbean was completed in six days. Urea treatment/toasting slightly reduced crude protein content of jackbean, but diets containing it at both 10% and 20% compared favourably with the control. Raw toasted jackbean significantly (P<0.05) depressed performance of the young broiler chicks at 20% dietary level.