As a skeleton component of plants, lignin is an organic macromolecule polymer that can be regenerated and naturally degraded. Annually, plant growth produces about 150 billion tons of lignin. In industrial processes such as paper and biomass‐refining industry, large amounts of lignin are formed as by‐products. Most of technical lignins are directly combusted to obtain heat, which not only is a waste of organic matter but also leads to environmental pollution and other issues. Interestingly, lignin can be used as slow‐release carriers and coating materials for fertilizers due to its excellent slow release properties as well as chelating and other functionalities. Preparation of lignin‐based slow/controlled release fertilizers can be achieved by sustainable chemical (ammoxidation, Mannich reaction, and other chemical modifications), coating (without or with chemical modification), and chelation modifications. This Review systematically summarizes the methods, mechanisms, and application of the above methods for preparing lignin‐based slow/controlled release fertilizers. Although the evaluation standards and methods of lignin‐based slow/controlled release fertilizers are not perfect, it is believed that more and more scholars will pay more attention to them to accelerate the development and application of lignin‐based slow/controlled release fertilizers, so as to improve their relevant standards. In short, there is an urgent need to improve the preparation process of lignin‐based slow/controlled release fertilizers and application as lignin‐based slow/controlled release fertilizers to production practice as soon as possible.

Field experiment was conducted to test the effect of ground covering rice production system (GCRPS) on rice yield, nitrogen use efficiency (NUE), and water utilization coefficient. Cultivating lowland rice variety in upland condition by using of plastic film (T1), paper film (T2), or rice straw mulching (T3) to cover the ground resulted in similar yield as for paddy rice (T5), but the yield was significantly greater than that of upland rice cultivation system without mulching (T4). Water utilization coefficient of mulching treatments (T1, T2, and T3) increased from 178% to 219% compared to T5. About 69% irrigation water was saved when shifting lowland paddy rice into GCRPS. The nitrogen (N) nutrition state in flag leaf (FL) and 3rd leaf backward (LBW) showed no statistical difference between T1 and T5. However, N content of FL and 3rd LBW of T1 was significantly greater than that of T4. The amount of N uptake, NUpE and NUE of T1, T2, and T3 was remarkably greater than those of T4. Increment of nitrogen fertilizer utilization efficiency (INfUE) increased 12.1%, 12.5%, and 8.7% in treatments of T1, T2, and T3, respectively. Therefore, cultivating lowland rice variety with mulching treatment not only increased water coefficient, but increased NfUE significantly under upland condition as well.

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Abstract. This paper presents a componentwise convex splitting scheme for numerical simulation of multicomponent two-phase fluid mixtures in a closed system at constant temperature, which is modeled by a diffuse interface model equipped with the Van der Waals and the Peng-Robinson equations of state (EoS). The Van der Waals EoS has a rigorous foundation in physics, while the Peng-Robinson EoS is more accurate for hydrocarbon mixtures. First, the phase field theory of thermodynamics and variational calculus are applied to a functional minimization problem of the total Helmholtz free energy. Mass conservation constraints are enforced through Lagrange multipliers. A system of chemical equilibrium equations is obtained which is a set of second-order elliptic equations with extremely strong nonlinear source terms. The steady state equations are transformed into a transient system as a numerical strategy on which the scheme is based. The proposed numerical algorithm avoids the indefiniteness of the Hessian matrix arising from the second-order derivative of homogeneous contribution of total Helmholtz free energy; it is also very efficient. This scheme is unconditionally componentwise energy stable and naturally results in unconditional stability for the Van der Waals model. For the Peng-Robinson EoS, it is unconditionally stable through introducing a physics-preserving correction term, which is analogous to the attractive term in the Van der Waals EoS. An efficient numerical algorithm is provided to compute the coefficient in the correction term. Finally, some numerical examples are illustrated to verify the theoretical results and efficiency of the established algorithms. The numerical results match well with laboratory data.

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