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Legume green manure (LGM) is an excellent organic amendment conducive to soil quality and nutrient cycling; however, the use of LGM was once repealed in the rain-fed agriculture of northern China. The objective was to investigate the effects that planting LGM would bring and whether it would affect other fertilization regimes regarding the productivity and water and nutrient use efficiencies of succeeding crops. A short-term (2016–2019) field experiment was established with a split-plot design in the Loess Plateau of China, which included ten treatments consisting of two planting systems (main treatments)—conventional winter wheat monoculture (G0) and planting and incorporating LGM followed by winter wheat planting (G)—and five fertilization regimes (sub-treatments)—no fertilization (CK), basal fertilization with chemicals N, P and K (NPK), basal fertilization plus wheat straw return (NPK + S), basal fertilization plus farmyard manure application (NPK + M), and basal fertilization plus wheat straw return plus farmyard manure application (NPK + S + M). The results demonstrated that compared with G0, the G did not remarkably affect the total water consumption (WC) and water use efficiency (WUE) across the three trial wheat seasons. Specifically, during the third wheat season, the winter wheat yield of G increased by 7.5% more than that of G0 (p < 0.05). G primarily increased the N concentration in winter wheat and universally increased the uptake of N, P and K by 18.8%, 11.7% and 18.8%, respectively. The apparent use efficiencies (AUEs) of chemicals N, P and K under G were 88.0%, 102% and 93.2% higher than those under G0 (p < 0.05). In contrast, the wheat yields of NPK, NPK + S, NPK + M and NPK + S + M were 14.3%, 22.2%, 26.4% and 19.5%, respectively, higher than those of CK. The WC and WUE increased under NPK, NPK + S, NPK + M and NPK + S + M relative to the CK (p < 0.05). Compared with CK, the NPK, NPK + S, NPK + M and NPK + S + M primarily increased the N concentration in winter wheat and universally increased the uptake of N, P and K (p < 0.05). The AUEs of N, P and K were increased by 44.3–75.3%, 72.4–103% and 128–160%, respectively, by NPK + S, NPK + M and NPK + S + M compared with CK. In conclusion, the revival of planting LGM during the fallow period was considered an appropriate measure in the Loess Plateau and similar rain-fed regions due to its ability to improve the growth and nutrient utilization of subsequent winter wheat even in the short term, as well as the lack of negative effects exerted on other organic amendments in its effectiveness.

Decentralized treatment of wastewater has been identified as an area of growth for cyber-enabled sensing and control. One such system that would benefit from embedded cyber components is urine diversion. This research sought to create a cyber-physical system for wastewater collection and treatment. Two subsystems were integrated into the CPS: sensing and actuation. Real-time sensing using low-cost pH and conductivity sensors was used to monitor urine chemistry. Actuation was used to deliver urine to the system and to control urine chemistry. Once integrated, the system used the sensing data to determine when to actuate urine chemistry control pumps. By using urine diversion as a test case, two demonstrations were able to show the applicability of the system created. The first demonstration was able to characterize the flow characteristics of the physical system. The second demonstration was able to mimic and inhibit urea hydrolysis under realistic conditions. Ultimately, the use of this novel CPS approach was able to confirm the benefits of sensing and actuation in wastewater collection and treatment within buildings.

Potassium (K) input is essential for the improvement of soil fertility in agricultural systems. However, organic amendment may differ from mineral K fertilization with respect to modifying the soil K transformation among different fractions, affecting soil K availability. We conducted a 60-day lab incubation experiment to evaluate the response of soil K dynamics and availability in various fractions with a view to simulating crop residue return and chemical K fertilization in an Anthrosol of northwest China. The tested soil was divided into two main groups, no K fertilization (K0) and K fertilization (K1), each of which was subjected to four straw addition regimes: no straw addition (Control), wheat straw addition (WS), maize straw addition (MS), and both wheat straw and maize straw addition (WS+MS). Soil K levels in the available (AK) and non-exchangeable (NEK) fractions were both significantly increased after K addition, following the order of K>WS>MS. Fertilizer K was the most efficient K source, demonstrating a 72.9% efficiency in increasing soil AK, while wheat and maize straw exhibited efficiencies of 47.1% and 39.3%, respectively. Furthermore, K fertilization and wheat and maize straw addition increased the soil AK in a cumulative manner when used in combination. The mobility factor (MF) and reduced partition index (IR) of soil K were used to quantitate the comprehensive soil K mobility and stability, respectively. Positive relationships were observed between the MF and all relatively available fractions of soil K, whereas the IR value of soil K correlated negatively with both MF and all available fractions of soil K. In conclusion, straw amendment could be inferior to mineral K fertilization in improving soil K availability when they were almost equal in the net K input. Crop straw return coupled with K fertilization can be a promising strategy for improving both soil K availability and cycling in soil-plant systems.

Organic input is a widely recognized amendment for soil organic carbon (SOC) sequestration and soil quality improvement. A short-term(2-yr) field experiment was conducted to evaluate the effects of green manure (GM) planting, wheat (Triticum aestivum L.) straw return and farmyard manure application, and their interactions on SOC sequestration in a rain-fed winter wheat system in Northwest China. Ten combinations of two cultivation practices, conventional wheat monoculture (G0) and green manure-winter wheat rotation (G), and five fertilization methods during the wheat season: (a) no basal fertilization (B0), (b) basal chemical fertilization (B), (c) basal chemical fertilization plus wheat straw return (B + S), (d) basal chemical fertilization plus manure application (B + M) and (e) basal chemical fertilization plus wheat straw return and manure application (B + S+ M) were tested. Compared with their controls, M, S, and G increased the SOC stock in the 0-to-10-cm soil layer by an average of 20.7, 6.8, and 6.3%, respectively, and increased in the 10-to-20-cm soil layer by an average of 15.8, 4.7, and 6.6%, respectively. Manure exhibited a 55.9% carbon sequestration efficiency (CSE) in the 0-to-20-cm soil layer, followed by GM and wheat straw which exhibited CSEs of 27.7 and 19.3%, respectively. Nevertheless, combinations of G, M, and S, increased the SOC stock in cumulative manners without significant interactions. Positive relationships (P < .05) existed between the SOC sequestration and cumulative C input in both G0 and G. Therefore, G, S, and M, and their combinations were all effective for SOC sequestration in this cropping system. The G + M+ S was optimal for promoting SOC sequestration over the short term. [ABSTRACT FROM AUTHOR]

Foliar ZnSO4 application has been shown to be effective for increasing Zn concentration in wheat (Triticum aestivum L.) grain but is time and energy consuming. For promoting adoption of this practice by growers, a field experiment was conducted in two seasons to evaluate the effects of foliar Zn combined with six commonly used pesticides (three insecticides and three fungicides) applied at flowering or milk stage on Zn concentration and bioavailability in wheat grain and its milling fractions. Grains were fractionated into flour and bran for analysis of Zn, phytic acid (PA), and other nutrients (protein, P, K, Fe, and Mn). The results showed that foliar application of Zn together with various pesticides, irrespective of pesticide type, was as effective as foliar Zn application alone in improving Zn concentrations in whole grain and in its milling fractions. Combined foliar application of Zn with pesticides did not increase PA concentration but significantly increased the estimated Zn bioavailability in flour by 79.2%, in bran by 95.4%, and in grain by 94.5%. Zinc foliar application (with or without pesticides) at milk stage resulted in a higher Zn concentration and bioavailability in whole grain than Zn applied at flowering stage. There were no adverse effects of combined foliar application of Zn and pesticides on grain yield and other nutrients. Therefore, foliar Zn application can be safely applied with commonly used fungicides or insecticides (particularly at milk stage) to enrich Zn of the whole grain and particularly the flour and represents a useful practice for overcoming human Zn deficiency. [ABSTRACT FROM AUTHOR]

Returning the crop residues has been documented to increase soil carbon storage. However, the impacts of different straw return strategies on soil C fractions and sustainable crop productivity are not fully understood. Here, we investigated the impact of different residue management systems on grain yields, SOC sequestration, and soil C fractions in a wheat (Triticum aestivum L.)-maize (Zea mays L.) double cropping system over 6 yr. The straw return strategies included no straw return (CK), conventional wheat straw return (WC), modified wheat straw return (WM), conventional maize straw return (MC), modified maize straw return (MM), conventional straw return for both wheat and maize (WC+MC), and modified straw return for both wheat and maize (WM+MM). The annual average grain yields of maize and wheat when compared to crop residue removal were increased by 32.5 and 50.5% than when the wheat straw and corn stover was not harvested, respectively. Compared to the initial value, the SOC stock increased over a 6 yr by 16.4% period when the wheat straw and corn stover was not harvested. The concentrations of microbial biomass C, very labile C, labile C, KMnO4-oxidizable C, and C management index were increased by returning the crop residue. Overall, the results suggested that the integrated and modified return strategy of both wheat and maize straw is an optimal way of sustainable crop production under the intensive wheat-maize double cropping rotation in the North-central Plain of China. [ABSTRACT FROM AUTHOR]

Straw return is a promising method for managing soil organic carbon (SOC) in agricultural soils and thus may promote sustainable land use. However, the optimal straw-return strategy for economically sustainable grain production in intensive winter wheat (Triticum aestivum L.)-summer maize (Zea mays L.) cropping systems remains uncertain. A 4-yr field experiment was conducted in the central North China Plain to determine the effects of straw return on SOC stock and lability, soil enzyme activity, and grain yield, and to further evaluate the sustainability of crop production in intensive wheat-maize double-cropping systems. Four treatments were tested: no straw return (NR), return of wheat straw (WR), return of maize straw (MR), and return of both wheat and maize straw (WR+MR). Compared with the initial value, SOC stocks significantly increased by 2.8, 5.4, and 13.1% in WR, MR, and WR+MR, respectively, and significantly decreased by 2.9% in NR. Stocks of KMnO4-oxidizable C and microbial biomass C; activities of soil invertase, protease, and dehydrogenase; and the C management index were significantly higher with than without straw return and followed the order NR < WR < MR < WR+MR. Yields of wheat and maize were highest in WR+MR, but economic sustainability was higher in WR and MR relative to NR and WR+MR. Our results indicate that return of either wheat or maize straw is sufficient to maintain SOC levels and may be the optimal strategy for economically sustainable grain production in the central North China plain. [ABSTRACT FROM AUTHOR]