Pengaruh pemupukan N terhadap serapan dan efisiensi penggunaan N, serta hasil padi hibrida

Pemupukan N pada padi hibrida menjadi krusial mengingat varietas padi hibrida sangat responsif, sehingga harus diketahui dosis yang tepat untuk menghasilkan produksi yang tinggi. Penelitian ini bertujuan untuk mengkaji pengaruh dosis N terhadap serapan N, efisiensi penggunaan N, dan hasil padi hibrida. Penelitian menggunakan Rancangan Acak Kelompok yang diulang tiga kali. Faktor pertama adalah varietas padi hibrida yang terdiri dari Varietas Mapan P05, Varietas SL-8 SHS Sterling, dan Varietas Intani 602. Faktor kedua adalah dosis pemupukan N yang terdiri dari kontrol tanpa pemupukan N, dosis N 100 kg ha-1, dan dosis N 200 kg ha-1. Terdapat respon yang beragam antar varietas padi hibrida terhadap taraf pemupukan N, Serapan N, efisiensi penggunaan N tertinggi yang dihasilkan oleh varietas Intani 602 masing-masing sebesar 138,57 %, dan 36,13%. Serapan N tanaman padi tertinggi dicapai pada dosis N 100 kg ha-1, dan efisiensi penggunaan N tertinggi pada dosis N 200 kg ha-1. Hasil gabah tertinggi dicapai pada varietas Mapan P05 sebesar 7,42 t ha-1, dan dosis pemupukan N 100 kg ha-1 memberikan hasil tertinggi sebesar 7,47 t ha-1. Implikasi dari penelitian ini bahwa dosis nitrogen 100 kg ha-1 dapat menjadi acuan sebagai dosis pemupukan N varietas padi hibrida di Indonesia. Hybrid rice is responsive to nitrogen, so it’s necessary to find the optimum dose to optimize the production. The aim of this research was to examine the effect of nitrogen on N uptake, N use efficiency, and yield of hybrid rice. This study used a randomized block design with three replications. The first factor consisted of the Mapan P05 variety, the SL-8 SHS Sterling variety, and Intani 602 variety. The second factor was Nitrogen dosage consisted of control, 100 kg ha-1, and 200 kg ha-1. There were various responses among hybrid rice varieties to the level of fertilization. The highest N uptake and N use efficiency was achieved in the Intani 602 variety at 138.57% and 36.13%, respectively. The highest N uptake was achieved at 100 kg ha-1 of N, and the highest N use efficiency was at 200 kg ha-1. The highest yield was achieved in the Mapan P05 variety (7.42 t ha-1), and the dose of N at 100 kg ha-1 gave the highest yield (7.47 t ha-1). The implication of this research is that the nitrogen dose of 100 kg ha-1 can be used as a reference for hybrid rice varieties fertilizer in Indonesia.

Improvement of Root Characteristics Due to Nitrogen, Phosphorus, and Potassium Interactions Increases Rice (Oryza sativa L.) Yield and Nitrogen Use Efficiency

Although nitrogen (N), phosphorus (P), and potassium (K) co-application improves crop growth, yield, and N use efficiency (NUE) of rice, few studies have investigated the mechanisms underlying these interactions. To investigate root morphological and physiological characteristics and determine yield and nitrogen use parameters, rhizo-box experiments were performed on rice using six treatments (no fertilizer, PK, N, NK, NP, and NPK) and plants were harvested at maturity. The aboveground biomass at the elongating stage and grain yield at maturity for NPK treatment were higher than the sum of PK and N treatments. N, P, and K interactions enhanced grain yield due to an increase in agronomic N use efficiency (NAE). The co-application of N, P, and K improved N uptake and N recovery efficiency, exceeding the decreases in physiological and internal NUE and thereby improving NAE. Increases in root length and biomass, N uptake per unit root length/root biomass, root oxidation activity, total roots absorption area, and roots active absorption area at the elongating stage improved N uptake via N, P, and K interactions. The higher total N uptake from N, P, and K interactions was due to improved root characteristics, which enhanced the rice yield and NUE.

Improving Nitrogen Use Efficiency—A Key for Sustainable Rice Production Systems

Fertilizer use and genetic improvement of cereal crops contributed to increased yields and greater food security in the last six decades. For rice, however, fertilizer use has outpaced improvement in yield. Excess application of nutrients beyond crop needs, especially nitrogen (N), is associated with losses to the environment. Environmental pollution can be mitigated by addressing fertilizer overuse, improving N use efficiency, while maintaining or improving rice productivity and farmers' income. A promising approach is the site-specific nutrient management (SSNM), developed in the 1990s to optimize supply to meet demand of nutrients, initially for rice, but now extended to other crops. The SSNM approach has been further refined with the development of digital decision support tools such as Rice Crop Manager, Nutrient Expert, and RiceAdvice. This enables more farmers to benefit from SSNM recommendations. In this mini-review, we show how SSNM can foster sustainability in rice production systems through improved rice yields, profit, and N use efficiency while reducing N losses. Farmer adoption of SSNM, however, remains low. National policies and incentives, financial investments, and strengthened extension systems are needed to enhance scaling of SSNM-based decision support tools.

Liming Optimizes Nitrogen Fertilization in a Maize-Upland Rice Rotation under No-Till Conditions

Liming and N fertilization are common practices for optimizing crop yields in tropical agriculture, but the adequate N rate to ensure crop development, enhance yields and N use efficiency, and improve soil chemical properties has not been established for grass rotation. We assessed the optimal N fertilizer rate for combination with liming in an agricultural system composed of two grasses (maize and rice) in rotation under no-till (NT) conditions. Four N rates (0, 50, 100, and 150 kg N·ha−1) were tested under two liming conditions. Maize (11 Mg·ha−1) and rice (5 Mg·ha−1) yields were highest with lime and 150 kg N·ha−1 applications. At 18 months after liming, lime application increased soil pH. In addition, combining liming with N fertilization further increased SOM content at all N rates. Lime increased available P, exchangeable Ca2+ and Mg2+, and BS at N rates of 0, 50, and 100 kg N·ha−1. Overall, combining liming and N fertilization is beneficial for grass crops under NT conditions, as evidenced by enhanced maize and rice N use efficiency and yields. N fertilization rates of 100 and 150 kg N·ha−1 under lime amendment provided the best improvements in crop yields in this cropping system.

Potential of Chamomile recutita Plant Material to Inhibit Urease Activity and Reduce NH3 Volatilization in Two Agricultural Soils

The large amount of ammonia released during agricultural application of urea fertilizer can result in a partial loss of applied nitrogen, having a detrimental effect on air quality. Although Chamomile recutita has nitrogen transformation inhibitory properties, providing potential agricultural and environmental benefits, the full extent of the effects of the major constituents of this plant on urease activity and NH3 volatilization in soils is currently unknown. Soil incubation experiments were established using 2-Cyclopenten-1-one and Eugenol, two major constituents of C. recutita, to evaluate their effects on inorganic soil nitrogen pools, urease activity, and NH3 volatilization in grey desert soil and red soil. An application rate of 0.25 g N kg−1 soil fertilizer was applied as urea with and without additives. An unfertilized treatment was also included as a control. In order to compare results, N(butyl) thiophosphoric triamide (NBPT), a common synthetic urease inhibitor, was also used. NBPT, 2-Cyclopenten-1-one and Eugenol were applied at a rate of 0.00125 g kg−1 soil (equivalent to 0.5% N). The results indicated that the rate of urea hydrolysis was higher in grey desert soil compared to red soil. Soil in the urea-only treatments recorded urea hydrolysis to be almost complete within seven days of application. The rate of hydrolysis was inhibited by the two natural compounds, and higher concentrations of urea were maintained for more than two weeks. Soil amended with the two materials exhibited strong soil urease inhibition in both soil treatments (75.1% in the alkaline grey desert soil and 72.8% in the acidic red soil). The strongest inhibitory effect occurred one to three days after incubation in the Eugenol treatment. Moreover, the inhibitory effects of Cyclopenten-1-one and Eugenol were superior to that of NBPT in the two soils. Cyclopenten-1-one and Eugenol also significantly reduced soil NH3 emissions by 14.2 to 45.3%, especially in the acidic red soil. Molecular docking studies confirmed inhibition mechanisms, highlighting that natural compounds interacted with the amino acid residues of the urease active center. This action resulted in the urease active pocket being blocked, thereby inhibiting enzyme activity. Overall, our findings suggest that 2-Cyclopenten-1-one and Eugenol are both capable of hindering urease activity and reducing the risk of N loss in the two tested soils. Results highlight their applicability as urease inhibitors and their effect in delaying the release of ammonia nitrogen, thereby increasing fertilizer N use efficiency. However, in order to fully assess N use efficiency and the N balance due to the presence of Chamomile extract in soil-crop systems, further field scale investigations are required.