Millet nutrient use efficiency as affected by natural soil fertility,mineral fertilizer use and rainfall in the West African Sahel

Field experiments were designed to investigate the effectiveness of integrated soil fertility management (ISFM), comparing fertilizer use efficiency and its impact on millet, cultivated close to the homestead (“infields”) and away from the homestead (“outfields”). Millet yields and response to N (0, 30, and 60 kg ha⁻¹) and P (0, 15, and 30 kg ha⁻¹) were determined on nine infields and nine outfields over a period of 3 years (from 1999 to 2001) in the southern Sahel of Niger. Rainfall was 650, 470, and 370 mm during the three successive years, interaction between decreasing rainfall and millet yield performance was also analyzed. While soil organic carbon (1.5 g kg⁻¹ on outfields and 1.6 g kg⁻¹ on infields) and pH-H₂O (4.8 on outfields and 5.1 on infields) were comparable, total-N, plant available P (measured as P-Olsen and P-Bray), and exchangeable Ca, K, and Mg levels were higher on infields as compared to outfields. Without fertilizer, average grain yield (GY) and stover yield obtained on infields were three times as high as on outfields. GY across years and fertilizer treatments was higher on infields as compared to outfields (P < 0.001). Average yield was 800 kg ha⁻¹ on outfields and 1,360 kg ha⁻¹ on infields (P < 0.001). On outfields, average GY was stagnant over the 3-year experimental period. Despite declining rainfall, millet GY across all treatments gradually increased over time on infields (P < 0.001). P fertilization alone resulted on both field types to steadily and substantial yield increases while yield response to N fertilization was only obvious when fertilizer P was applied. With no fertilizer applied, N uptake on infields (19 kg N ha⁻¹) was more than twice as high as on outfields (7 kg ha⁻¹), and P uptake was four times higher on infields (3 kg ha⁻¹) than on outfields (0.8 kg ha⁻¹). Indigenous soil N supply was on average 24 kg N ha⁻¹ on outfields and 46 kg N ha⁻¹ on infields. Average value for indigenous soil P supply was 4 kg P ha⁻¹ on infields and 2 kg ha⁻¹ on outfields. Apparent recovery of fertilizer N applied varied considerably among treatments and ranged from 17 to 23% on outfields and 34 to 37% on infields (P < 0.001). Average apparent recovery of fertilizer P applied was significantly higher (P < 0.001) on infields (31%) than on outfields (18%) over the 3-year growing period, illustrating ISFM-induced positive effect on millet nutrient N and P use. Results indicate higher inherent soil fertility, underline ISFM-induced drought tolerance of soils on infields as compared to outfields, and highlight the crucial role of fertilizer P (especially on outfields) for millet production. These call for site-specific nutrient management and support, even under low rainfall conditions, the potential value of fertile infields for efficient and productive external input use and sustainable millet production in West African Sahel.     

Techno-economic analysis of a biodiesel production process from vegetable oils

Biodiesel, which is defined as the monoalkyl esters of long chain fatty acids derived from a renewable lipid feedstock, has received considerable attention worldwide as a medium-term alternative to diesel fuel obtained from petroleum. Biodiesel can be produced by the transesterification of vegetable oils or animal fats using short-chain alcohols in the presence of a suitable catalyst and glycerol is the only byproduct obtained in significant quantities. In this work a techno-economic analysis of a process that produces biodiesel from vegetable oils is presented with the aim to investigate the dependence of the critical profitability indicators on the production capacity.     

Vertical distribution of heavy metals in wastewater-irrigated vegetable garden soils of three West African cities

Application of untreated wastewater to irrigate urban vegetable gardens is raising serious concern about possible health risks associated with the consumption of these vegetables particularly with regard to the concentrations of heavy metals (HM) in their edible portions. The soil concentrations of cadmium (Cd), chromium (Cr), copper (Cu), nickel (Ni), lead (Pb) and zinc (Zn), were investigated in seven vegetable gardens from the three West African cities of Kano (Nigeria), Bobo Dioulasso (Burkina Faso) and Sikasso (Mali). Also determined were input–output balances of Cd and Zn from five vegetable gardens under 30 years of wastewater irrigation in Kano. In these gardens Cd (2.3–4.8 mg kg⁻¹) and Zn (13–285 mg kg⁻¹) concentrations throughout the profile attained unsafe levels. The concentrations of Cu (0.8–18 mg kg⁻¹), Cr (1.8–72 mg kg⁻¹), Ni (0–17 mg kg⁻¹) and Pb (0.6–46 mg kg⁻¹) were below the safety thresholds for arable soils. Overall, concentrations of Zn, Cd, Pb and Ni were higher in Kano than in Bobo-Dioulasso and Sikasso. Input–output analyses in Kano indicated that irrigation wastewater contributed annually 400–3,700 g Cd ha⁻¹ and 7,200–22,300 g Zn ha⁻¹, fertilizer 30–2,100 g Cd ha⁻¹ 50–17,600 g Zn ha⁻¹, harmattan dust 0.02–0.4 g Cd ha⁻¹ and 40–200 g Zn ha⁻¹ while 300–500 g Cd ha⁻¹ and 2,700–4,700 g Zn ha⁻¹ came from rainwater inputs. Input–output calculations subtracting the amounts of HM taken out in vegetable biomass and that lost to leaching from total inputs yielded an annual net positive balance of 700–4,160 g Cd ha⁻¹ and 9,350–39,700 g Zn ha⁻¹. If such balances remain unchanged for another 10–20 years vegetables raised in these garden fields are likely to be unsuitable for human consumption.     

Horizontal nutrient fluxes and food safety in urban and peri-urban vegetable and millet cultivation of Niamey,Niger

Urban and peri-urban agriculture (UPA) has often been accused of being nutrient inefficient and producing negative externalities. To investigate these problems for the West African capital Niamey (Niger), nutrient inputs through fertilizer and manure to 10 vegetable gardens and 9 millet fields and nutrient offtakes through harvests were quantified during 24 months, and contamination of irrigation water and selected vegetables with faecal pathogens and heavy metals was determined. Annual partial horizontal balances for carbon (C), nitrogen (N), phosphorus (P) and potassium (K) amounted to 9,936 kg C ha⁻¹, 1,133 kg N ha⁻¹, 223 kg P ha⁻¹ and 312 kg K ha⁻¹ in high input vegetable gardens as opposed to 9,580 kg C ha⁻¹, 290 kg N ha⁻¹, 125 kg P ha⁻¹ and 351 kg K ha⁻¹ in low input gardens. In high input millet fields, annual surpluses of 259 kg C ha⁻¹, 126 kg N ha⁻¹, 20 kg P ha⁻¹ and 0.4 kg K ha⁻¹ were recorded, whereas surpluses of 12 kg C ha⁻¹, 17 kg N ha⁻¹, and deficits of −3 kg P ha⁻¹ and −3 kg K ha⁻¹ were determined for low input fields. Counts of Salmonella spp. and Escherichia coli yielded above threshold contamination levels of 7.2 × 10⁴ CFU 25 g⁻¹ and 3.9 × 10⁴ CFU g⁻¹ in lettuce irrigated with river water and fertilized with animal manure. Salmonella counts averaged 9.8 × 10⁴ CFU 25 g⁻¹ and E. coli 0.6 × 10⁴ CFU g⁻¹ for lettuce irrigated with wastewater, while these pathogens were not detected on vegetables irrigated with pond water. These results underline the need for urban gardeners to better adjust the nutrients applied to crop requirements which might also reduce nutrient accumulations in the soil and further in the edibles parts of the vegetables. Appropriate pre-treatment of irrigation water would help improve the quality of the latter and enhance the food safety of vegetables determined for the urban markets.     

Fertiliser strategies for improved nutrient use efficiency on sandy soils in high rainfall regimes

Fertiliser application strategies for maize (Zea mays L.) production on sandy soils under high rainfall regimes need to be carefully designed to minimise nutrient losses through leaching and maximise crop yield. Experiments were conducted to determine N, P, and K leaching in sandy soils with 3–6% clay in surface layers under maize production, and the effectiveness of different N, P, and K fertiliser timing and splitting strategies on leaching of N, P, and K and on maize yield. In a column experiment on an Oxic Paleustult (Korat series) with 3% clay, leaching of N, P, and K from fertiliser (114N-17P-22K in kg ha⁻¹) was significant under simulated rainfall, but decreased to negligible levels with 3–5 split applications of fertiliser. Maize N and K uptake increased with 3–5 split applications, but not P uptake. Despite continued intense rainfall and further fertilizer additions, leaching was not recorded after day 30, and this was attributed to the effect of plant water uptake on reducing deep drainage. Split applications of fertilizer maintained NP and K in the 0–30 cm layer during 30–60 days when maize nutrient demand was likely to be at its highest, while in the recommended fertilizer regime NPK in the surface layers declined after 30 days. In a field experiment on an Oxic Paleustult (Korat series) with 6% clay, 3–4 splits of fertiliser increased N and K uptake and increased maize yields from 3.3 to 4.5 Mg ha⁻¹. Postponing basal fertiliser application from pre-planting to 7–15 days after emergence increased uptake of N, P, and K and grain yield emphasising the greater risk of nutrient losses from fertiliser applied at planting than later. Strategies designed to reduce the amount of nutrients applied as fertiliser at planting, such as split application and postponing basal application can decrease the risk of leaching of N, P, and K from fertiliser and improve nutrient use efficiency, and grain yield of maize on sandy soils under high growing season rainfall regimes.     

An original transesterification route for fatty acid ester production from vegetable oils in a solvent-free system

Wax ester production from a long-chain alcohol and methyl ester has been investigated with an immobilized thermostable lipase (lipozyme IM from Novo Nordisk). The transesterification reaction rate was monitored in solvent-free medium that was exclusively composed of the reactants and the enzyme. The transesterification is performed by simply mixing the two substrates in various stoichiometric amounts at a temperature range from 55 to 65°C under constant stirring in the presence of low concentrations of enzyme preparation (0.12 to 2%, w/w). Long-chain reactants produce waxes of high molecular mass that induce low solubility and high viscosity. On average, high transesterification yields are obtained (around 95%). Thermodynamic parameters involving substrate concentration and temperature have also been investigated. The balance between optimal working temperature and the molar ratio of substrates in such a complex medium appears to be 60°C, with a molar ratio methyl oleate/stearyl alcohol of 1:0.5. Substrate inhibition due to stearyl alcohol has been observed. A study of kinetic parameters has confirmed these results.     

Fertilizer management effects on oil palm yield and nutrient use efficiency on sandy soils with limited water supply in Central Kalimantan

Identifying optimal fertilizer management to ensure high nutrient use efficiency is important to reduce negative environmental impacts in oil palm (Elaeis guineensis) cultivation. A 4-year fertilizer trial was established in an oil palm plantation, located at a sandy area with occasional monthly water deficit in Central Kalimantan. We examined the responses of oil palm yield and nutrient use efficiency to fertilizer application frequency (standard frequency of 1–2 times yr^?1 versus 4 times yr^?1) and rate (standard rate of 136, 12, and 200 kg ha^?1 yr^?1 of N, P and K, respectively versus 80% of standard rate). There were no treatment effects on annual yield in fresh fruit bunch, bunch number, or individual bunch weight. Increasing fertilizer frequency did not increase nutrient use efficiency at the last 2 years of the trial. In contrast, reducing fertilizer rate resulted in higher nutrient use efficiency in K, compared to the standard treatment and increasing fertilizer frequency. Average concentrations of N, P, K, Mg, Ca, and Cl in leaflet under all treatments were above critical levels both in the beginning and at the end of the trial. Monthly yield in fresh fruit bunch correlated positively with soil water balance with correlation coefficients of 0.24–0.29, during the developmental period of inflorescence sex differentiation at 28–30 months before fruit maturity. Our study provides useful information for fertilizer management optimization in sandy areas with occasional water deficit, corresponding to most of the new expansion areas of oil palm in Southeast Asia.     

Modelling the quantitative evaluation of soil nutrient supply, nutrient use efficiency, and fertilizer requirements of wheat in India

Wheat yields in many parts of India are stagnant. The main reason forthis is conventional blanket fertilizer recommendation, lower fertilizer useefficiency, and imbalanced use of fertilizers. Estimation of fertilizerrequirements based on quantitative approaches can assist in improving wheatyields and increasing nutrient use efficiency. We used the QUEFTS (QUantitativeEvaluation of Fertility of Tropical Soils) model for estimation of nitrogen(N),phosphorus (P), and potassium (K) requirements and fertilizer recommendationsfor a target yield of wheat. The model considers the interactions of N, P, andK, and climate adjusted potential yield of the region. Published data fromseveral field experiments dealing with N, P, and K conducted during the years1970 to 1998 across wheat-growing environments of India, covering a wide rangeof soil and climatic conditions, were used to reflect the environmentalvariability. The relationships between indigenous N, P, and K supply and soilorganic carbon, Olsen P, and ammonium acetate-extractable K, respectively, wereestablished. The required N, P, and K accumulation in the plant for 1 tonnegrain yield was 23.1, 3.5, and 28.5 kg, respectively, suggestinganaverage NPK ratio in the plant dry matter of about 6.6:1:8.1. The constants forminimum and maximum accumulation (kg grain kg^–1) of N (27 and60), P (162 and 390), and K (20 and 59) were derived as the standard modelparameters in QUEFTS for fertilizer recommendation for irrigated wheat in thetropical and subtropical regions of India. Relationships of apparent recoveryefficiencies of fertilizer N, P, and K with levels of their application werealso determined. The observed yields of wheat with different amounts of thesenutrients were in good agreement with the values predicted by the model,indicating that the model can be used for fertilizer recommendations.     

Improving nutrient use efficiency from decomposing manure and millet yield under Plinthosols in Niger

To improve synchronicity between nutrients released from the decomposing manure with millet nutrient requirement under zaï technique, a 2-year field experiment was conducted at the International Crops Research Institute for the Semi-Arid Tropics Research Station, Sadoré, Niger. The treatments consisted of factorial combination of two rates of cattle manure (200 and 300 g per zaï hole), three periods of manure application (before planting, at planting and 15 days later) and two rates of mineral fertilizer [nitrogen (N), phosphorus (P) and potassium (K) 15–15–15] applied at 6 g per zaï hole and a control, without mineral fertilizer). Manure dry mass losses did not significantly differ among manure application periods in 2013. However, in 2014 the highest manure dry mass loss occurred when manure was applied before planting with 70% of manure applied being decomposed at millet maturity stage (115 days after litterbag installation) followed by manure applied at planting with almost 50% of dry mass losses. The quantities of N and P absorbed by millet at tillering stage represented, 61, 52 and 33% of N released and 15, 12 and 15% of P released at the same time when manure was applied before planting, at planting and 15 days after planting, respectively. Application of manure before planting increased on an average millet grain yield by 16 and 20% and N utilization efficiency by 25 and 31% compared to application of manure at planting and 15 days after planting respectively. Addition of mineral fertilizer induced a synergetic effect on millet grain yield (p = 0.002). Millet grain yields increased on average by 5, 17 and 57% when 6 g per zaï pit of NPK fertilizer were added to plots receiving manure application before planting, at planting and 15 days after planting, respectively. We conclude that application of manure prior to planting satisfies better millet nutrients demand, thereby increasing nutrient use efficiency and grain yield under zai pits.     

提高水射流喷嘴清洗效率的理论分析

主要从高压水射流基本参数出发,分析高压水射流清洗机喷嘴效率提高途径．以便使我国生产使用的数千台清洗机发挥出更高的效率,让广大清洗机用户获得更大的经济效率。     

提高硫基复合肥生产中氮的利用率

结合生产实践,从工艺操作条件(中和度、干燥温度、混酸密度、返料倍数)、产品氮含量、控制法、原料配方(硫酸、磷酸用量,氨与尿素用量比例)、磷酸杂质、产品水分控制法、装置稳定运行等方面分析其对高浓度硫基复合肥氮利用率的影响,提出提高氮利用率的一些做法和控制要求。     

Nitrogen balances and nitrogen use efficiency of intensive vegetable rotations in South East Asian tropical Andisols

Nitrogen fertilizer application rates in intensive vegetable production in (South) East Asia have increased exponentially over the past decades, including in the low income countries. While there have been reports of excessive N inputs from e.g. Vietnam, Thailand and Indonesia, very little quantitative knowledge exists on the real extent of the problem. We calculated N balances and agronomic N use efficiencies (ANUE) for a number of typical intensive vegetable rotations in the highlands of Central Java, Indonesia, on fertile Andisols, both for individual cropping cycles (short term) as for 6 consecutive cropping cycles (long term). This was done for farmers practice (FP) treatments, and improved practice (IP) treatments, where N fertilization was significantly reduced. Yields were in general similar in FP and IP, but tended to be slightly higher in IP, with some significant differences. Both the short and long term N balances were always positive and usually very high. Short term N balances ranged from 9 to 559 kg N ha⁻¹ and 219 to 885 kg N ha⁻¹ in IP and FP, respectively, while short term ANUE ranged from 8 to 67 and 4 to 39% in IP and FP, respectively. Long term N balances ranged from 627 to 1,885 kg N ha⁻¹ and 962 to 3,808 kg N ha⁻¹ in IP and FP, respectively, indicating a massive excess of N supply especially in FP. N balances can thus be drastically reduced with no negative impacts on yield, on the contrary. Soil mineral N in the 0–25 cm layer was in general not very high (6.5–38.8 mg N kg⁻¹ soil) and not systematically different between IP and FP, probably as a result of excessive NO₃ ⁻ leaching. Therefore, topsoil mineral N seems to have only limited indicator value under these conditions. Because denitrification losses in these soils are not very high, most N in excess of the crop requirements will be lost by leaching. Quantitative data on N balances as obtained here may be used to sensitize policy makers and farmers about the threat of current farming practices to the environment, and to improve economic performance.     

盐酸解析与水碱洗系统的酸、水生产平衡

以40万t/a PVC为例,对氯化氢的消耗量与盐酸的解析量进行了物料衡算。     

Crop productivity and nutrient use efficiency as affected by long-term fertilisation in North China Plain

Nutrient inputs into crop production systems through fertilisation have come under increased scrutiny in recent years because of reduced nutrient use efficiency and increased environmental impact. Fifteen years of experimental data on dynamics of N, P and K in soil, crop yield and nutrient uptake from nine fertilisation treatments at Zhengzhou, North China Plain, were used to analyse the contribution of different fertilisation treatments to crop yield, nutrient use efficiency and accumulation of nutrients in soil. The results showed that both N and P were limiting factors for crop growth. Without additional N and P fertilisation, only a very low yield level (ca 2 t ha⁻¹ for wheat and 3 t ha⁻¹ for maize) could be maintained. To achieve the potential productivity (i.e. yield level free of water and nutrient stresses) of wheat (6.9 t ha⁻¹) and maize (8.3 t ha⁻¹), wheat would need, on average, 170 kg N ha⁻¹, 32 kg P ha⁻¹ and 130 kg K ha⁻¹, while maize would need 189 kg N ha⁻¹, 34 kg P ha⁻¹ and 212 kg K ha⁻¹. The N and P demands correspond well to the N and P levels supplied in one of the fertilisation treatments (NPK), while K deficiency could occur in the future if no crop residues were returned or no extra K was applied. On average under this NPK treatment, 80% of N and 71% of P could be recovered by the wheat–maize system. Treatments with nutrient inputs higher than the NPK treatment and treatments without combination of N and P have led to accumulation of N and P in the soil profile. The input levels of N and P in the NPK treatment are recommended in fertiliser management, with additional K to avoid future soil K deficiency.     

电厂循环水系统水处理方式调整及其效果分析

针对电厂原循环水系统运行过程中暴露出的不足和隐患,通过实施运行方案调整和系统完善,有效地解决了凝汽器铜管腐蚀泄漏问题,延长了设备的使用寿命,满足了电厂长周期安全运行的需要.     

半导体Z反应光解水制氢的光能转换效率及研究进展

通过介绍人工半导体Z反应的原理,综述该类型反应体系,包括模拟PSI催化剂（PS1[H2]）、模拟PSII催化剂（PS2[O2]）和介体（mediator） 应用于人工模拟光解水制氢的研究进展,重点阐述此三者在Z反应中所起的作用及其电子传递机理的发展现状,并通过估算不同介体的光能转换效率比较各反应系统的优缺点,指出无介体Z反应系统的电子传递机理、非贵金属助剂的制备、在光催化还原二氧化碳和光电催化中的应用是未来Z反应研究的重点。     

Controlled-release fertilizers to increase efficiency of nutrient use and minimize environmental degradation - A review

Total world consumption of fertilizer N, P₂O₅, and K₂O in 1990/1991 was 78, 37, and 26 million tons per annum, respectively, with a projected yearly increase of demand of about 2 to 3%. Trends in crop production (maize and wheat) in the last four decades show that N application rates increased about 15 times whereas its accumulation in grain increased only 3 to 4 times. At the same time nutrient recovery by crops remained relatively low (e.g. about 50% for N). This represents a potentially alarming situation from environmental, economic and resource conservation points of view and indicates an urgent need for improving efficiency of fertilizer use. Anticipated benefits from slow/controlled release fertilizers (SRF/CRF) are addressed through two main processes: a. nutrient availability in the plant-soil system as affected by the interaction/competition between: plant roots, soil microorganisms, chemical reactions and pathways for loss; and b. matching nutrient release with plant demand. The various aspects of fertilization and environmental hazards associated with SRF/CRF and factors affecting nutrient use efficiency (NUE) are discussed in the light of these controlling processes. Environmental aspects include: pollution by nitrate, phosphate, and emission/volatilization of N₂O or NH₃; quality of food and fibers; and factors affecting soil degradation. Agronomic or physiologic aspects include: reduced losses of nutrients, labour saving, reduction of specific stress or toxicity, increased availability of nutrients and induction of synergistic effects between specific chemical forms of nutrients (e.g. interaction of mixed NH₄/NO₃ nutrition with K, effects of physiological acidification of the rhizosphere on P and Fe availability etc.). Despite the environmental and agronomic benefits offered by SRF/CRF their practical use in agriculture is still very limited. Possible measures which may encourage their use in practice are: a better assessment of expected benefits; attainment of improved technologies or concepts for producing more efficient and less expensive SRF/CRF; optimal design of fertilizer compositions to induce synergistic effects; better understanding of the mechanisms which control nutrient release; construction of conceptual and mathematical models for predicting release rates and patterns under both laboratory and field conditions, for supporting the technologist, farmer and environmentalist in their decision making.