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【Objective】 Subsurface drain is a drainage system widely used in northwestern China to keep the groundwater below the critical depth and facilitate soil salt leaching. This paper presents an experimental study on the combined effect of drain depth and spacing on soil salt leaching in a representative oasis in Yanqi Basin. 【Method】 The drains were buried at the depth of 1.2 or 1.5 m, with the spacing being 20, 30 or 40 m. Overall, there were six treatments. For each treatment, we measured the spatial changes in soil salt contents before and after the leaching, which were then used to analyze the variation in salt leaching efficiency between different treatments. 【Result】 ① When initial soil moisture was at the field capacity, leaching could quickly saturated the soil and displace the water in the soil above the drains. There were no significant correlations between soil moisture content and the depth and spacing of the drains. ② Salt leaching from the top 0-60 cm soil layer was significantly related to the depth and spacing of the drains. The spacing and depth of the drains combined to affect soil salt removal rate. When the spacing was the same, increasing the burial depth of the drains enhanced salt removal from the 0-60 cm soil layer; when the burial depth of the drains was the same, salt removal rate from the 0-60 cm soil layer was the highest when the spacing was 30 cm (P0.05). Compared to the burial depth of 1.2 m, the burial depth of 1.5 m considerably improved the drainage efficiency and accelerated soil salt removal. 【Conclusion】 For maximum soil salt removal rate, the optimal depth and spacing of the subsurface drains for the study area was 1.5 m and 30 m, respectively.

Scientific fertilization is an important technical means of achieving high and stable peanut yields. Using soil testing and formula fertilization, the “3414” optimal regression design was used and included 14 nitrogen (N), phosphorus (P), and potassium (K) fertilization treatments. Ternary quadratic functions of the fertilizer effect were established according to three-season field experiments and the regression analysis of fertilizer–yield function was performed to explore the optimal fertilizer application mode and ratio for peanuts under mulched drip irrigation (MDI), and a suitable fertilizer application system was established. The ternary quadratic equation relating peanut yield (y) and the fertilizer application rates of N (N), P (P2O5), and K (K2O) was obtained after fitting, i.e., y = 2912.528 + 21.432N + 16.324P + 6.181K − 0.051N2 − 0.109P2 − 0.061K2 + 0.017NP + 0.023NK + 0.086PK, and significance analysis and typicality assessment were performed. The model R 2 was 0.9709, both values are extremely significant (p < 0.01), which indicates that the obtained ternary quadratic fertilizer effect function is typical and could be used for statistical purposes and fertilization recommendations. Three quadratic fertilizer effect functions were obtained. Among them, the equation for K is extremely significant, and the equations of N and P are significant. According to the assumption that the marginal yield is zero and the marginal profit is zero, the fertilizer application rate with the maximum yield, the fertilizer application rate with the best economic benefits, and the corresponding yields were obtained. The optimal fertilizer application rate predicted by the ternary quadratic fertilizer effect function was relatively high, so the three quadratic fertilizer effect functions were used for prediction. Under the test conditions, the recommended fertilizer application rates for peanuts under MDI are 256.6 kg N per ha, 164.2 kg P2O5 per ha, and 213.2 kg K2O per ha, the recommended fertilization ratio is 1:0.64:0.83, and the recommended ratio under formula fertilization is 23:15:19. The study has developed a data-based decision support system for Xinjiang drip-irrigated peanut, which assists farmers and agricultural managers in making more scientific and precise fertilization decisions based on the specific growth requirements of the crops and soil conditions. This evidence-based methodology enhances the precision of agricultural management, which is conducive to increasing crop yields while reducing resource wastage and environmental impact. However, multipoint and multiyear experiments are still needed to ensure that the findings are adaptable to the diverse soil conditions and fluctuating climate patterns that may be encountered in practice.

The availability of phosphorus (P) fertilizer applied to soil can diminish rapidly because of the complex soil P immobilization processes. However, the quantitative distribution of fertilizer P in the soil P fractions is not fully understood. Here, two experiments were conducted in a greenhouse using 32P‐labelled KH2PO4 to (i) quantify the distribution of P fertilizer in soil fractions, microorganisms and maize shoots grown in contrasting soils; (ii) characterize the effect of planting maize on soil P fractions and (iii) determine the amount of plant P derived from fertilizer vs. soil. Depending on the soil type, 74.1%–84.1% of the labelled P was retained in the soil, 11.4%–14.5% was found in maize shoots and 0.7%–4.5% was present in microorganisms. Distribution of applied P in the soil P fractions was dependent on soil type, with most P present as NaOH‐Pi and residual‐P in the Red soil, and as HCl‐P in the Fluvo‐aquic soil. Root‐mediated processes were involved in mobilisation of residual‐P in all three soils, with significant depletion of NaOH‐Pi in the Red soil, NaOH‐Pi and HCl‐P in the Black soil, and HCl‐P in the Fluvo‐aquic soil. The plant P derived from fertilizer and soil increased with increasing P addition rates in all three soils. In the soils with low‐P availability, fertilizer contributed more P to plants than soil, whereas in the initially high‐P soil, the opposite occurred. In conclusion, the partitioning of fertilizer P to various soil P fractions is dependent on the soil type, and the contribution of P derived from fertilizer to maize P uptake was related inversely to the soil legacy P. [ABSTRACT FROM AUTHOR]

Integrated optical filters are key components in various photonic integrated circuits for applications of communication, spectroscopy, etc. The dichroic filters can be flexibly cascaded to construct filters with various channel numbers and bandwidths. Therefore, the development of high-performance and compact dichroic filters is crucial. In this work, we develop the dichroic filters with 1.49/1.55-µm channels by an inverse design. Benefiting from a search-space-dimension control strategy and advanced optimization algorithm, our efficient design method results in two high-performance dichroic filters without and with subwavelength gratings (SWGs). The comparison suggests that SWGs in filters can be useful for loss reduction and footprint compression by dispersion engineering. The developed dichroic filter with SWGs exhibits measured bandwidths of 26/29 nm, excess losses of < 0.5 dB, and crosstalks of <-10 dB with a compact footprint of 2.5 × 22.0 µm 2 . It has advantages in performance or compactness compared to the previously reported counterparts. A triplexer with a footprint of 10.5 × 117 µm 2 is developed based on the dichroic filters, also showing decent overall performance and compactness.

Ultrathin C 3 N 5 nanosheets with enhanced photocatalytic methylene blue (MB) degradation and H 2 -evolution performance were prepared from thermal treatment of 3-amino-1,2,4-triazole (3-AT) and NH 4 Cl followed with a protonate procedure. The characterization results revealed that the protonating process could contribute to the exfoliation of C 3 N 5 with large surface area, the effective charge transfer capability and the modified band structure. The as-prepared C 3 N 5 nanosheets exhibited enhanced properties in photocatalytic reactions such as MB photodegradation and H 2 -evolution from water splitting. This study offered a feasible route to prepare highly-efficient two-dimensional photocatalyst, which could be applied potentially for implementation in wide range of energy generation and environmental applications., (Copyright © 2020 Elsevier Inc. All rights reserved.)