A comparison of the biological activities of ethyl acetate fractions from the stems and leaves of Penthorum chinense Pursh

Penthorum chinense Pursh (PCP) is a popular traditional medicinal plant in China, widely used for the treatment of a variety of liver diseases. Although it has been long recognized that the main active elements of PCP are contained in ethyl acetate fraction (EAF), little is known so far in terms of the relative effectiveness of EAF derived from the stems versus leaves of this plant. In the current study, we prepared EAF by reflux extraction and sequential extraction from the stems (SEAF) and leaves (LEAF) of PCP and tested their hepatoprotective efficacies. The extract rates and flavonoid contents of LEAF were higher than those of SEAF. EAFs (>50 μg·mL⁻¹) prevented lipid accumulation in cells and protected against lipotoxicity injury when the concentration exceeded 25 μg·mL⁻¹. More than 95% free radicals released by 2,2-diphenyl-1-picrylhydrazyl (DPPH) were eliminated by 25 μg·mL⁻¹ SEAF and 50 μg·mL⁻¹ LEAF, respectively. Further, EAFs (25 μg·mL⁻¹) also showed protective antioxidant effects, with the activity of LEAF being significantly higher than that of SEAF. EAFs (10 mg·mL⁻¹) also showed similar unspecific bacteriostatic activity. In comparison with SEAF, LEAF contained more flavonoids and had a higher anti-oxidation capability and for these reasons we suggest it should be better for clinical use.     

Phosphorus status,use and recycling in a Chinese peri-urban region with intensive animal husbandry and cropping systems Results from case study in a Sino-German applied research collaboration project

The Sino-German research collaboration project, “Recycling of organic residues from agricultural and municipal origin in China” (2008–2012), comprising different interdisciplinary research groups, and also German small and medium-sized enterprises, aimed at developing integrated strategies and solutions for the recycling of organic residues in China. In an intensive crop-livestock agricultural region in the Shunyi District of Beijing, five typical cropping systems were investigated. The research was conducted in the form of analyses of phosphorus (P) in soil, plants, animal feed, animal products, manures, mineral and organic fertilizers and the derivation of the corresponding nutrient balances and P flows. The mean annual P balance surplus was 492 kg·ha⁻¹·yr⁻¹ P for the vegetable production system, significantly higher (P<0.05) than that for orchards (130 kg·ha⁻¹·yr⁻¹P) and cereal crops (83 kg·ha⁻¹·yr⁻¹ P). Plant-available P (Olsen-P) concentrations of topsoils (0–20 cm) had good correlations with the amounts of P applied (from mineral and organic sources). Compared to results from the Second Chinese National Soil Survey of 1981, mean concentrations of available P in soils of 19 plots investigated in Shunyi District increased 10-fold (from 7.3 to 60 mg·kg⁻¹) from 1981 to 2009. On average, the critical limit for Olsen-P concentrations (>30 mg·kg⁻¹) that can lead to increased risk of P loss was exceeded in all five cropping systems. With feed additives, the “natural background value” (Chinese Environmental Quality Standard for Soils) of copper and zinc in topsoils was exceeded at several sites. Screening for several substances in the veterinary antibiotic classes of sulfonamides, tetracyclines, and fluoroquinolones revealed widespread topsoil contamination. Calculated livestock densities were 10.6 livestock units per ha arable land in 2007. Animal husbandry is increasingly conducted in large operations, making traditional ways of reuse difficult to apply. Comparing three management systems for treatment of organic residues from a pig farm via aerobic (composting) or anaerobic (biogas) treatment in a life cycle assessment, the resulting cropland demand for a sustainable land application of biogas effluent varied between 139 and 288 ha·yr⁻¹, well above the cropland area owned by the farm (10 ha). The mismatch problems in the above context between business-as-usual and improving performance are framed and discussed as (1) the mismatch between centralized animal husbandry and smallholder farming, (2) the mismatch between livestock density and cropland, (3) nutrient (including P) recycling and increasing organic matter content versus energy production, (4) subsidies for compost production and biogas, as well as (5) advances in the regulatory framework in China.     

INTENSIFICATION OF GRASSLAND-BASED DAIRY PRODUCTION AND ITS IMPACTS ON LAND,NITROGEN AND PHOSPHORUS USE EFFICIENCIES

• Monitoring data of>5000 dairy farms collected and examined in uniform manner. • Environmental performances of farms influenced by government regulations. • N and P surpluses at farm level remained about constant with intensity level. • N and P use efficiencies at farm, herd and soil increased with intensity level. • Accounting for externalization of off-farm feed production affects NUE and PUE. • Ammonia emissions per kg milk decreased with the level of intensification. Many grassland-based dairy farms are intensifying production, i.e., produce more milk per ha of land in response to the increasing demand for milk (by about 2% per year) in a globalized market. However, intensive dairy farming has been implicated for its resources use, ammonia and greenhouse gas emissions, and eutrophication impacts. This paper addresses the question of how the intensity of dairy production relates to N and P surpluses and use efficiencies on farms subjected to agri-environmental regulations. Detailed monitoring data were analyzed from 2858 grassland-based dairy farms in The Netherlands for the year 2015. The farms produced on average 925 Mg·yr⁻¹ milk. Milk production per ha ranged from<10 to>30 Mg·ha⁻¹·yr⁻¹. Purchased feed and manure export strongly increased with the level of intensification. Surpluses of N and P at farm level remained constant and ammonia emissions per kg milk decreased with the level of intensification. In conclusion, N and P surpluses did not differ much among dairy farms greatly differing in intensity due to legal N and P application limits and obligatory export of manure surpluses to other farms. Further, N and P use efficiencies also did not differ among dairy farms differing in intensity provided the externalization of feed production was accounted for. This paper provides lessons for proper monitoring and control of N and P cycling in dairy farming.     

Characterization of grain cadmium concentration in indica hybrid rice

As a consequence of contamination of soil with heavy metals, cadmium accumulation in grain is of great concern worldwide, but especially in southern China. It is important to evaluate the Cd accumulation potential of grain before or when examining and approving new cultivars. An evaluation method and criteria for verifying Cd accumulation potential in rice are proposed, and the Cd accumulation potential of 56 mid-season indica hybrids collected from the provincial cultivar trials in 2016 were investigated. Genotype, environment and their interactions strongly affected the variation in grain Cd accumulation. Two hybrids were identified as slightly Cd accumulating. Hybrids with slight Cd accumulation potential would be suitable for safe grain production on polluted land (total Cd under 2.0 mg·kg⁻¹) in Hunan Province (China) and should be considered for new cultivar evaluation and approval. This evaluation method and criterion could be applied for certifying Cd accumulation potential of rice cultivars.     

A potential solution for food security in Kenya: implications of the Quzhou model in China

Poor soil fertility due to low nutrient inputs is a major factor limiting grain production in Kenya. Increasing soil fertility for crop productivity in China has implications for food security in Kenya. The purpose of this study was therefore to investigate the historical patterns of grain production, nutrient inputs, soil fertility and policies in Quzhou, a typical agricultural county on the North China Plain, and to compare grain production in Quzhou County and Kenya to identify a potential approach for increasing grain production in Kenya. Grain yields in Quzhou increased from 1 to 3 t·ha⁻¹ between 1961 and 1987 by increasing manure application accompanied by small amounts of chemical fertilizer after soil desalinization. There was a further increase from 3 to 5 t·ha⁻¹ up to 1996 which can be mainly attributed to chemical fertilizer use and policy support. Hence, a beneficial cycle between soil fertility and plant growth in Quzhou grain production was developed and strengthened. In contrast, there was only a slight increase in grain yields in Kenya over this period, resulting from low soil fertility with limited external nutrient inputs, a consequence of poor socioeconomic development. It is suggested that grain yields in Kenya would likely be boosted by the development of a self-reinforcing cycling between soil fertility and plant growth with manure and chemical fertilizer use if supported by policy and socioeconomic development.     

Modeling temperature and moisture dependent emissions of carbon dioxide and methane from drying dairy cow manure

Greenhouse gas emissions due to biological degradation processes of animal wastes are significant sources of air pollution from agricultural areas. The major environmental controls on these microbe-induced gas fluxes are temperature and moisture content. The objective of this study was to model the effects of temperature and moisture content on emissions of CO₂ and CH₄ during the ambient drying process of dairy manure under controlled conditions. Gas emissions were continuously recorded over 15 d with paired fully automated closed dynamic chambers coupled with a Fourier Transformed Infrared gas analyzer. Water content and temperature were measured and monitored with capacitance sensors. In addition, on days 0, 3, 6, 9, 12 and 15, pH, moisture content, dissolved organic carbon and total carbon (TC) were determined. An empirical model derived from the Arrhenius equation confirmed high dependency of carbon emissions on temperature and moisture content. Results indicate that for the investigated dairy manure, 6.83% of TC was lost in the form of CO₂ and 0.047% of TC was emitted as CH₄. Neglecting the effect of temperature, the moisture contents associated with maximum gas emissions were estimated as 0.75 and 0.79 g·g⁻¹ for CO₂ and CH₄, respectively.     

畜禽有机肥磷素在冬小麦上替代化肥磷当量研究

【目的】近年来化学磷肥的过量施用不仅造成了磷矿资源的浪费,还增加了环境污染的风险。畜禽粪便是一种很好的化肥磷替代资源,但由于其成分复杂,转化过程影响因素较多,畜禽粪便中磷素相对化肥磷素的有效性一直存在不同结论。明确畜禽粪便中磷素替代化肥磷当量,能够确定有机肥磷素替代化肥磷素的准确比例,为有机肥磷素的合理施用提供数据支撑。【方法】选取腐熟的猪粪、鸡粪、牛粪和化肥为材料,施磷（P₂O₅）量均设置6个水平,分别为0、20、40、60、80、100 mg·kg^-1干土,利用土柱栽培试验在冬小麦上研究粪肥磷和化肥磷对小麦产量、磷素吸收利用及土壤速效磷含量的影响,并对3种粪肥中磷素替代化肥磷素的相对替代当量进行统计分析。【结果】（1）3种粪肥中有机磷和无机磷含量存在较大差异,猪粪、鸡粪和牛粪中有机磷占总磷的比例分别为25.9%、17.6%和56.5%。从磷组分看,牛粪中磷素形态主要以活性磷（H₂O-P和NaHCO₃-P）为主,而鸡粪和猪粪以高稳定态磷（HCl-P）为主。（2）等磷施用粪肥和化肥条件下,各处理间小麦产量无显著差异。化肥处理的小麦磷素吸收量略高于3种粪肥处理。（3）本试验条件下,若以磷素的当季回收率作为参考指标,鸡粪、猪粪和牛粪中磷素相对化肥磷素的等效值分别为80.3%、84.3%和90.4%。以化肥磷用量与籽粒产量、生物量、籽粒吸磷量及地上部吸磷量的回归关系函数计算的3种粪肥磷素的相对替代当量,猪粪的相对替代当量分别为90.0%、93.6%、80.6%、80.2%,鸡粪的相对替代当量分别为78.4%、87.9%、73.4%、67.6%,牛粪的相对替代当量分别为89.6%、99.9%、90.0%、87.3%。（4）粪肥磷和化肥磷均可提高土壤中速效磷含量,但短期内粪肥磷对土壤中速效磷含量的提高稍弱于化肥磷。【结论】本试验条件下综合几种计算磷素相对替代当量的方法,猪粪能够替代85.7%的化肥磷素,鸡粪能够替代77.6%的化肥磷素,而牛粪能够替代91.4%的化肥磷素。     

Symbiotic performance,shoot biomass and water-use efficiency of three groundnut (Arachis hypogaea L.) genotypes in response to phosphorus supply under field conditions in Ethiopia

Phosphorus is a key nutrient element involved in energy transfer for cellular metabolism, respiration and photosynthesis and its supply at low levels can affect legume nodulation, N₂ fixation, and C assimilation. A two-year field study was conducted in Ethiopia in 2012 and 2013 to evaluate the effects of P supply on growth, symbiotic N₂ nutrition, grain yield and water-use efficiency of three groundnut genotypes. Supplying P to the genotypes significantly increased their shoot biomass, symbiotic performance, grain yield, and C accumulation. There was, however, no effect on shoot δ¹³C values in either year. Compared to the zero-P control, supplying 40 kg·ha⁻¹ P markedly increased shoot biomass by 77% and 66% in 2012 and 2013, respectively. In both years, groundnut grain yields were much higher at 20 and 30 kg·ha⁻¹ P. Phosphorus supply markedly reduced shoot δ¹⁵N values and increased the %Ndfa and amount of N-fixed, indicating the direct involvement of P in promoting N₂ fixation in nodulated groundnut. The three genotypes differed significantly in δ¹⁵N, %Ndfa, N-fixed, grain yield, C concentration, and δ¹³C. The phosphorus × genotype interaction was also significant for shoot DM, N content, N-fixed and soil N uptake.     

Effect of long-term fertilization on phosphorus fractions in different soil layers and their quantitative relationships with soil properties

Investigating the dynamics and distribution of soil phosphorus (P) fractions can provide a basis for enhancing P utilization by crops.  Four treatments from a 29-year long-term experiment in black soil with maize cropping were involved in this study: no fertilizer (CK), inorganic nitrogen and potassium (NK), inorganic nitrogen, phosphorus, and potassium (NPK), and NPK plus manure (NPKM).  We analyzed soil P fractions in different soil layers using a modified Hedley sequential method.  The long-term NPKM treatment significantly increased total P by 0.6–1.6 times in the different soil layers.  The Olsen-P concentration far exceeded the environmental threshold for soil Olsen-P (50.6 mg kg^–1) in the NPKM treatment in the 0–60 cm soil profile.  Moreover, the concentrations and proportion of labile and partially labile inorganic P (Pi) fractions (i.e., NaHCO₃-extracted Pi, NaOH-extracted Pi, and dilute HCl-extracted Pi) to the sum of all P fractions (Pt) in the 0–60 cm soil profile were higher in the NPKM treatment than in the NPK treatment, indicating that manure could promote the transformation of non-labile into more labile forms of P in soil, possibly by manure reducing P fixation by soil particles.  Soil organic matter, Mehlich-3 extractable iron (Fe), and organic-bound aluminum were increased by fertilization, and were the main factors influencing the differences in the P fractions in the 0–20 cm soil layer.  Soil mineral components, i.e., free Fe oxide and CaCO₃, were the main factors influencing the P fractions in the subsoil.  The soil P transformation process varied with soil layer and fertilization.  Application of manure fertilizer can increase the labile (Olsen) P concentrations of the various soil layers, and thus should reduce the mineral P fertilizer requirement for crop growth and reduce potential environmental damage     

Polyaniline–polypyrrole nanocomposites using a green and porous wood as support for supercapacitors

Wood is an ideal type of support material whose porous structure and surface functional groups are beneficial for deposition of various guest substances for different applications. In this paper, wood is employed as a porous support, combined with two kinds of conductive polymers (i.e., polyaniline (PANI) and polypyrrole (PPy)) using an easy and fast liquid polymerization method. Scanning electron microscope observations indicate that the PANI–PPy complex consists of nanoparticles with a size of ~20 nm. The interactions between oxygen-containing groups of the wood and the nitrogen composition of PANI–PPy were verified by Fourier transform infrared spectroscopy. The self-supported PANI–PPy/wood composite is capable of acting as a free-standing supercapacitor electrode, which delivers a high gravimetric specific capacitance of 360 F·g⁻¹ at 0.2 A·g⁻¹.     

不同动物粪肥的磷素形态特征及有效性分析

我国规模化养殖业的快速发展导致动物粪肥数量急剧增加,合理利用畜禽粪肥中的大量磷素,不仅可节约磷矿资源,而且避免由于粪肥直接排放和农田过量施用所带来的水体面源污染问题。本研究结合调研工作,采集了52个典型养殖场的76个动物粪肥样品,采用Hedley 磷分组方法,系统分析了不同粪肥中磷素含量及其组分特征,评价不同形态磷素在土壤中的移动性及其环境风险,为合理磷素管理提供参考。结果表明:不同动物粪肥的全磷含量差异很大,猪粪、鸡粪、鸭粪、牛粪和羊粪的平均含量分别为22.5、13.7、12.9、9.6 g P·kg^-1和7.5 g P·kg^-1,其中粪肥中的有机磷占总磷的比例分别为33.1%、41.5%、66.4%、28.1%和36.8%。非反刍动物粪肥(猪粪、鸡粪、鸭粪)中全磷含量和有机磷含量分别为反刍动物粪肥(牛粪和羊粪)中全磷和有机磷含量的1.7~3.0 倍和2.1~3.0 倍,以鸡鸭粪肥中有机磷占全磷的比例最高;非反刍动物粪肥C/P 比(19~29)明显低于反刍动物粪肥C/P 比(38~45),其中的磷素更易矿化;依次采用H₂O、NaHCO₃、NaOH 和HCl作为提取剂提取动物粪肥的磷素组分,反刍动物粪肥中H₂O-P、NaHCO₃-P、NaOH-P、HCl-P 和残余态磷分别为总磷的27.8%、32.8%、18.1%、15.2%和6.1%;而非反刍动物粪肥中的各磷素组分的比例分别为24.6%、19.4%、12.7%、34.4%和8.9%;两者主要在NaHCO₃-P和HCl-P组分存在差异。综上所述,反刍动物粪肥中活性磷(H₂O-P 和NaHCO₃-P)的比例更高,超过总磷的60%,而非反刍动物粪肥更易矿化分解的特征导致其可以很快释放活性磷,两者均具有很高的磷素有效性。因此,长期而言,在等粪肥磷投入情况下,两者的环境风险差异不大;而在等粪肥用量情况下,非反刍动物粪肥中更高的磷素含量会导致更高的环境风险。     

不同有机物料对灌漠土重金属累积特征及作物效应的影响

【目的】 探讨长期施用有机物料对灌漠土中重金属含量、形态赋存特征及作物重金属含量的影响,为有机物料农业安全利用及土壤有机培肥中重金属累积控制提供理论依据和技术支持。【方法】 利用田间长期定位试验,研究鸡粪、牛粪、猪粪、菌渣、污泥和沼渣对灌漠土几种典型重金属元素含量、赋存形态及小麦植株中重金属含量的影响。【结果】 长期（7年）施用鸡粪、猪粪、污泥的处理显著增加了灌漠土中Cu、Zn含量,增加量为猪粪＞鸡粪＞污泥,其中Cu含量分别增加了62.20%、20.10%和10.26%,Zn含量分别增加了79.98%、39.24%和18.31%,并与施用年限呈显著正相关关系。3种有机物料施用下Cu平均每年累积速率为4.16、1.25和0.97 mg·kg ^-1·a ^-1,Zn平均每年累积速率为11.04、4.86和2.59 mg·kg ^-1·a ^-1。但施用上述3种有机物料对Cd、Cr、Pb和Ni含量没有显著影响。施用牛粪、菌渣和沼渣对灌漠土中重金属含量亦无显著影响。施用鸡粪、猪粪、污泥还显著影响了土壤中Cu、Zn赋存形态,增加了土壤中Cu、Zn各有效赋存形态的含量和占总量的比例,显著提高了灌漠土中Cu、Zn有效态的含量,显著增加了小麦根和秸秆中Cu、Zn的含量,其中猪粪影响最大。【结论】 猪粪、鸡粪、污泥长期施用可导致灌漠土中Cu、Zn快速累积并提高Cu、Zn的生物有效性,其中猪粪的作用尤为明显。在施用有机物料培肥土壤时,要特别关注其中Cu、Zn的含量,以确保土壤健康和可持续利用。     

Effects of phosphate fertilizer and manure on Chinese cabbage yield and soil phosphorus accumulation

The yield response of Chinese cabbage to phosphate fertilizer and manure was studied. The effect of over-application of phosphate fertilizer and manure on plant total phosphorus content and phosphorus accumulation in soil was also investigated. The experiment was arranged in a plastic barrel in the field for two years. Application of phosphate fertilizer at the rates of 150–600 mg·kg⁻¹ gave a yield increase of 14.9%–21.5% of Chinese cabbage. Application of manure at the rates of 33.3–-133.2 g·kg⁻¹ gave a yield increase of 18.2%–25.9%of the crop. There was no significant difference of yield response at the rates of 150, 300 and 600 mg·kg⁻¹ phosphate fertilizer, and no significant yield response to the application of phosphate fertilizer after applying manure. The total P content in Chinese cabbage was increased gradually with the rate increase of phosphate fertilizer and manure. Phosphorus was absorbed luxuriously by the plant with over-application phosphate fertilizer and manure. The content of total-P, Olsen-P, water-soluble P, biological available P in the soil was increased with the rate of phosphate fertilizer and manure. Organic phosphorus in the soil was increased by the application of manure. Olsen-P had high correlations with water-soluble-P and biological available-P, but there was a poor relationship between Olsen-P and organic-P. __________ Translated from Scientia Agricultura Sinica, 2006, 39(10): 2147–2153 [译自: 中国农业科学]     

A novel aldo-keto reductase gene, IbAKR, from sweet potato confers higher tolerance to cadmium stress in tobacco

High concentrations of Cd can inhibit growth and reduce the activity of the photosynthetic apparatus in plants. In several plant species, aldo-keto reductases (AKRs) have been shown to enhance tolerance to various abiotic stresses by scavenging cytotoxic aldehydes; however, few AKRs have been reported to enhance Cd stress tolerance. In this study, the gene IbAKR was isolated from sweet potato. The relative expression levels of IbAKR increased significantly (approximately 3-fold) after exposure to 200 mmol·L⁻¹ CdCl₂ or 10 mmol·L⁻¹ H₂O₂. A subcellular localization assay showed that IbAKR is predominantly located in the nucleus and cytoplasm. IbAKR-overexpressing tobacco plants showed higher tolerance to Cd stress than wild-type (WT). Transgenic lines showed a significant ability to scavenge malondialdehyde (MDA) and methylglyoxal (MG). In addition, proline content and superoxide dismutase activity were significantly higher and H₂O₂ levels were significantly lower in the transgenic plants than in the WT. Quantitative real-time PCR analysis showed that the reactive oxygen species (ROS) scavenging genes encoding guaiacol peroxidase (GPX), ascorbate peroxidase (APX), monodehydroascorbate reductase (MDHAR) and peroxidase (POD) were significantly upregulated in transgenic plants compared to WT under Cd stress. These findings suggest that overexpressing IbAKR enhances tolerance to Cd stress via the scavenging of cytotoxic aldehydes and the activation of the ROS scavenging system.     

Optimum nitrogen fertilization of Calophyllum inophyllum seedlings under greenhouse conditions

A greenhouse pot experiment was conducted to study the effects of nitrogen fertilization on Calophy- llum inophyllum seedlings grown with 0, 50, 100, 150, 200, 300, 400 and 600 mg N per seedling according to exponential functions. Seedling height, root collar diameter, leaf area and total biomass increased with increasing fertilization from 0 to 200 mg N per seedling and decreased with further increase in fertilization from 300 to 600 mg N per seedling. The net photosynthetic rate, stomatal conductance, intercellular CO₂ concentration and transpiration rate of C. inophyllum seedlings showed a unimodal parabolic trend, with peak values of 7.29 mmol·m⁻²·s⁻¹, 0.071 mol·m⁻²·s⁻¹, 220 mmol·mol⁻¹ and 1.34 mmol·m⁻²·s⁻¹, respectively, when the rate of fertilization was 200 mg N per seedling. Photosynthetic gas exchange parameters were significantly different among nitrogen treatments. Based on the critical values of leaf N and P concentration and N/P ratio, the optimum amount of nitrogen of C. inophyllum seedlings was 200–400 mg per seedling for leaf N and P concentration, and 100–400 mg per seedling for N/P ratio. It was concluded that 200–400 mg N per seedling was the most suitable nitrogen range for C. inophyllum seedlings.     

LIGHT INTERCEPTION AND USE EFFICIENCY DIFFER WITH MAIZE PLANT DENSITY IN MAIZE-PEANUT INTERCROPPING

• Intercropping intercepted more light than sole peanut but less than sole maize.• Maize light use efficiency (LUE) increased with plant density in the intercropping.• Intercropping did not affect LUE of maize but increased peanut LUE.Intercropping increases crop yields by optimizing light interception and/or use efficiency. Although intercropping combinations and metrics have been reported, the effects of plant density on light use are not well documented. Here, we examined the light interception and use efficiency in maize-peanut intercropping with different maize plant densities in two row configurations in semiarid dryland agriculture over a two-year period. The field experiment comprised four cropping systems, i.e. monocropped maize, monocropped peanut, maize-peanut intercropping with two rows of maize and four rows of peanut, intercropping with four rows of maize and four rows of peanut, and three maize plant densities (3.0, 4.5 and 6.0 plants m⁻¹ row) in both monocropped and intercropping maize. The mean total light interception in intercropping across years and densities was 779 MJ·m⁻², 5.5% higher than in monocropped peanut (737 MJ·m⁻²) and 7.6% lower than in monocropped maize (843 MJ·m⁻²). Increasing maize density increased light interception in monocropped maize but did not affect the total light interception in the intercrops. Across years the LUE of maize was 2.9 g·MJ⁻¹ and was not affected by cropping system but increased with maize plant density. The LUE of peanut was enhanced in intercropping, especially in a wetter year. The yield advantage of maize-peanut intercropping resulted mainly from the LUE of peanut. These results will help to optimize agronomic management and system design and provide evidence for system level light use efficiency in intercropping.     

不同磷肥对砂姜黑土和红壤磷库转化及冬小麦磷素吸收利用的影响

【目的】探究不同磷肥对土壤磷素形态转化及小麦磷素吸收利用效率的影响,为土壤-磷肥-作物体系磷肥精准匹配及高效利用提供理论依据。【方法】在砂姜黑土和红壤上设置不施磷（CK）、施用过磷酸钙（SSP）、钙镁磷肥（FMP）、磷酸二铵（DAP）、重过磷酸钙（TSP）和聚磷酸铵（APP）6个处理,研究小麦拔节期和开花期根际与非根际土壤中磷库转化特征及其与植株体内磷素累积利用的关系。【结果】砂姜黑土施用磷肥后土壤有效磷含量提高194%—662%,不同磷肥处理小麦根际土壤中有效磷含量为APP>TSP>DAP>FMP>SSP>CK处理。施用磷肥显著提升了小麦拔节期和开花期砂姜黑土中H2O-P和NaHCO3-Pi含量,降低Residual-P含量,其中H2O-P和NaHCO3-Pi含量与土壤有效磷含量呈显著正相关,TSP和APP处理在小麦拔节期对NaHCO3-Pi含量提升幅度最大,分别较不施磷提升了41.0和36.0 mg·kg-1。红壤施用磷肥后根际土壤有效磷含量提高84%—791%,其中DAP和TSP处理的土壤有效磷含量显著高于其他磷肥处理,红壤中根际土壤NaHCO3-P...     

我国东北地区有机肥资源分布特征与养分利用潜力分析

为了探究我国东北地区主要有机肥资源的区域分布特征及养分利用潜力,以国家统计局发布的农作物产量、畜禽饲养量等数据为基础,对黑龙江省、吉林省、辽宁省及内蒙古自治区部分地区2000—2020年秸秆及畜禽粪便的产量及氮磷钾养分含量进行整理分析,结合2020年该区域的农作物种植结构,探讨了秸秆和畜禽粪肥还田的养分利用潜力。结果表明：该区域秸秆资源（干基）主要来源于玉米（61.88%）,2000—2020年秸秆的年均产量为1.38×10⁸ t·a^-1,畜禽粪肥资源（鲜基）主要来源于牛粪（52.44%）,年均产量为2.87×10⁸ t·a^-1,玉米秸秆和牛粪主要集中于黑龙江省的哈尔滨市、绥化市等地区;秸秆资源总产量呈波动增加的趋势,尤其是2000—2013年呈线性增加趋势,而畜禽粪肥的年度总产量相对稳定。以2020年秸秆和畜禽粪肥当年最大养分利用效率计算,该地区秸秆和粪肥理论上可提供的有效氮、磷、钾分别为1.16×10⁶、3.05×10⁵、2.13×10⁶ t,对农作物养分需求的贡献分别为29.57%、38.28%、112.49%。研究表明,以秸秆和畜禽粪肥的最大养分利用效率计算,东北地区的有机肥资源仍无法满足农作物的养分需求。因此,合理优化作物种植结构、提高有机肥资源还田利用效率,是实现该区域种养结合和农业可持续发展的重要途径。     

EXPLORING THE RECYCLING OF MANURE FROM URBAN LIVESTOCK FARMS: A CASE STUDY IN ETHIOPIA

• Livestock manure was the main organic waste in urban and peri-urban areas.• Manure production will increase by a factor of 3–10 between 2015–2050.• Only 13%–38% of excreted N by livestock will be recycled in croplands.• Intensification of urban livestock production greatly increased N surpluses.• Reducing population growth and increasing livestock productivity needed.Urban population growth is driving the expansion of urban and peri-urban agriculture (UPA) in developing countries. UPA is providing nutritious food to residents but the manures produced by UPA livestock farms and other wastes are not properly recycled. This paper explores the effects of four scenarios: (1) a reference scenario (business as usual), (2) increased urbanization, (3) UPA intensification, and (4) improved technology, on food-protein self-sufficiency, manure nitrogen (N) recycling and balances for four different zones in a small city (Jimma) in Ethiopia during the period 2015-2050. An N mass flow model with data from farm surveys, field experiments and literature was used. A field experiment was conducted and N use efficiency and N fertilizer replacement values differed among the five types of composts derived from urban livestock manures and kitchen wastes. The N use efficiency and N fertilizer replacement values were used in the N mass flow model.Livestock manures were the main organic wastes in urban areas, although only 20 to 40% of animal-sourced food consumed was produced in UPA, and only 14 to 19% of protein intake by residents was animal-based. Scenarios indicate that manure production in UPA will increase 3 to 10 times between 2015 and 2050, depending on urbanization and UPA intensification. Only 13 to 38% of manure N will be recycled in croplands. Farm-gate N balances of UPA livestock farms will increase to>1 t·ha⁻¹ in 2050. Doubling livestock productivity and feed protein conversion to animal-sourced food will roughly halve manure N production.Costs of waste recycling were high and indicate the need for government incentives. Results of these senarios are wake-up calls for all stakeholders and indicate alternative pathways.     

磷肥和有机肥对白菜产量及土壤磷库的影响（征文）

采用2年的微区筒定位试验研究了磷肥和有机肥对白菜产量、白菜全磷、土壤全磷、有机磷、Olsen-P、水溶性磷及生物有效磷等的影响。结果表明，磷肥用量150～600 mg·kg-1土，白菜产量增加14.9%~21.5%； 有机肥用量33.3～133.2 g·kg-1土，白菜产量增加18.2%~25.9%；施用150、300、600 mg·kg-1磷肥和施用33.3、66.6、133.2 g·kg-1有机肥及施用有机肥基础上增施磷肥，白菜产量均无显著变化。施用磷肥和有机肥显著增加白菜的全磷量，大量施用磷肥和有机肥导致白菜对磷的奢侈吸收。随磷肥和有机肥用量的增加，土壤Olsen-P、水溶性磷、生物有效磷均显著增加；随有机肥用量的增加土壤有机磷显著增加。土壤Olsen-P与水溶性磷和生物有效磷呈显著正相关，与土壤有机磷无显著相关性。