Economic control of fertilizer in highly productive pastoral systems. II. Designing field trials with physiologically balanced fertilizer through subtractive pot experiments

Deficiencies in essential chemical elements were diagnosed for two soils in a pot trial, using a subtractive technique and two different test plants: perennial ryegrass for ‘major’ elements and white clover for ‘minor’ elements. This information was required in a pastoral area to permit field trials to be designed with a suitably fortified superphosphate as the fertilizer input. The trials themselves are wanted to provide economic advice soundly based in relation to nutritional needs of pasture plants and grazing animals. Accordingly, a complex argument has been developed to justify using simple 3-level trials with physiologically balanced fertilizer instead of conventional multilevel factorial types; also to show how the simple trials should be designed.     

Economic control of fertilizer in highly productive pastoral systems. I. A theoretical framework for the fertilization problem

A hypothetical model, based on plant physiology and termed ‘Mitscherlich-Liebig’, is proposed as a general solution to the problem of estimating an optimum fertilizer rate from results in a field trial; in combining the ideas of Liebig and Mitscherlich the model involves the following proposals:

1. Diminishing returns in a smooth exponential relation between input and output culminating in a yield-plateau.
2. The difference between this plateau and the ideal asymptotic maximum is the result of an unavoidable osmotic depression caused by salts in the root zone.
3. Liebigian nonsubstitution of one essential elemental nutrient by another.
4. Quantitative equivalence in output from essential inputs when each is expressed in terms of a physiologically standardized amount defined as a Baule unit.
5. Pooling response data according to a relative yield theory and the Baule unit concept, rather than grouping data according to a soil type theory and the concept of a response curve unique for the element concerned.

In addition to certain other biometrical implications, these concepts provide an explicit method for estimating the composition of a balanced fertilizer mixture, whereby a profit maximising calculation may be applied through the ratio: cost of applied fertilizer/price of harvested yield. This approach to the problem permits a formulation of fertilizer advice theoretically sound in plant physiology as well as economics.     

Economic control of fertilizer in highly productive pastoral systems. IV. An appropriate model for a stable upgraded state

Data from a stable upgraded grass-clover system were used to show that an exponential model, based on the ideas of Liebig and Mitscherlich, may be simplified to permit a prediction of yields over years through three constant parameters for the fertilizer effect and one varying parameter for the climatic effect; this result is in accord with the Mitscherlich relative yield theory. When the model was applied to an economic analysis of the data, the result emphasized the importance of the concept of an average year in calculating fertilizer recommendations; also, it became apparent that completely unfertilized plots should be excluded from field trials intended as a base for such economic advice.     

On-farm Evaluation of Biological Nitrogen Fixation Potential and Grain Yield of Lablab and Two Soybean Varieties in the Northern Guinea Savanna of Nigeria

Several legumes with high biological nitrogen fixation (BNF) potentials have been studied in on-station trials. The processes involved in BNF and the benefits of these species to crop production need to be evaluated using farmers' management practices in farmers' fields. An on-farm trial with 20 farmers was conducted in the northern Guinea savanna (NGS) of Nigeria. The aims were to evaluate the BNF potentials of an improved soybean variety (TGx 1448-2E) and a local variety (Samsoy-2) when inoculated with Bradyrhizobium strains, and of Lablab in farmer-managed and researcher-managed soybean-maize and Lablab-maize crop rotation systems. The level of soil P was generally low with more than 50% of the fields having less than the critical P level. The plant available P content was statistically significantly (P = 0.05) correlated with P in grain (r = 0.60), P in the shoot (r = 0.68), grain yield (r = 0.40) and nodule weight (r = 0.35). Variations in plant parameters (nodulation, shoot dry matter, percentage nitrogen derived from the air [%Ndfa], grain yield, and nutrient uptake) among and within farmers’ fields were attributed to differences in soil fertility and crop management. About 60% of the fields were moderately fertile, sufficient to support legume establishment, while about 30% of the farmers' fields had a low fertility level. For farmers in the study area to benefit from the BNF potentials of the legumes, an external P fertilizer input was necessary as well as suitable crop management practices because all parameters measured in the researcher-managed plots were higher than in the farmer-managed plots.     

The role of inorganic fertilizers and their management practices

Nutrient management is the key issue in sustainable soil fertility. N, P, K fertilization aims not only for a high economic return of the investment through optimized yield and quality, but also for minimum environmental hazards. The basic concept underlying integrated plant nutrition systems, is the maintenance and possible increase of soil fertility for sustaining enhanced crop productivity through optimal use of all sources of plant nutrients, particularly inorganic fertilizer, in an integrated manner and as appropriate to each specific ecological, social and economic situation. Much research has established the importance of fertilizers in increasing the fertility of soil and in influencing its productivity. It has been observed that applying fertilizers causes many changes in the soil, including chemical changes, that can positively or negatively influence its productiveness. Only a fraction of the fertilizer applied to the soil is taken up by the crop, the rest either remains in the soil or is lost through leaching, physical wash-off, fixation by the soil, or release to the atmosphere through chemical and microbiological processes. The critical information on the relative merits of different fertilization practices such as method of fertilizer placement, time and rate of application and type of fertilizers, is essential. Results from different field and laboratory experiments which helped to achieve maximum efficiency, in the most economical and sustainable way of fertilizer use to reduce the nutrient losses and production costs to the farmers and prevent environmental pollution are presented in the paper.     

水稻专用BB肥施用效果及运筹方法研究

根据江苏宿豫县土壤肥力状况及水稻需肥规律,研制推广水稻专用 ＢＢ肥（２０—８—１７）,在有代表性的土壤上进行试验。结果表明：施用水稻专用 ＢＢ肥,有利于稳定水稻群体,减轻病虫危害,增产效果显著,经济效益明显。运筹方法上以每公顷基施 ３７５ ｋｇ专用 ＢＢ肥加 ３７５ ｋｇ碳铵作返青肥,加 １５０ ｋｇ尿素作稳肥效果较好。     

《面喷施水溶性生物腐植酸有机肥对马铃薯产量的影响

通过设置不同追肥用量,研究了追施水溶性生物腐植酸有机肥对马铃薯产量的影响。结果表明：施用水溶性生物腐植酸有机肥后,与对照相比,马铃薯均有不同程度的增产,增幅范围为4.02%～43.51%,单株结薯数增加了0.1～1.0个/株,单株块茎重增加了0.007～0.080千克/株。叶面喷施水溶性生物腐植酸有机肥的增产效果随着用量的减少而减弱。当追肥用量为50.01 L/hm^2时,为最佳经济用量,其产投比达9.95,比C K提高12.91%;继续增加用量,经济效益反而有所下降。在马铃薯现蕾期后,连续喷施水溶性生物腐植酸有机肥能起到增产、增收的效果。     

测土施肥与肥料创新

测土施肥是一个系统工程，肥料创新是其中非常重要的环节。掺混型肥料成为适应测土施肥推广的肥料产品，为业界所关注。我国人多地少，复种指数高，新型缓控释肥料与我国国情相结合的就是“一茬作物（只施）一次肥”。同时，测土施肥还需要施肥机械与施肥技术的创新，实现平衡施肥与肥料深施。涂层缓释一次肥以其全新的缓释理念和养分管理模式，成为适应测土施肥的肥料新产品。     

Factors affecting the use of fertilizers and manure by smallholders: the case of Vihiga,western Kenya

Sub-Saharan Africa faces huge food supply challenges due to increasing human population, limited opportunities to increase arable land, and declining yields associated with continuously declining soil fertility. To cater for their food requirements, smallholders use only modest levels of inorganic fertilizers and rely to a large extent on manure, which is generally of low quality. To explore factors influencing fertilizer and manure use at the farm level, 253 farm households in Vihiga district of western Kenya were sampled. A pair of Tobit models was used to relate amounts of manure and fertilizer used to household variables. The results indicate that the use of both manure and fertilizer reciprocally influence each other and are strongly influenced by household factors, and also imply that manure and fertilizer uses are endogenous. Policy changes are required to (1) reduce the burden on farming alone in rural areas; (2) promote the use of higher-cost, higher-value inputs such as fertilizers; (3) improve access to input and output markets; and (4) encourage farmer education so as to promote sustainable soil fertility management. Improved understanding of the biophysical and socioeconomic environment of smallholder systems can help target sustainable soil fertility interventions more appropriately.

中国西北地区肥料使用和生产现状及问题

利用统计资料和农户调查资料综合分析了中国西北地区肥料使用和生产现状及问题。结果表明,西北地区虽然可耕地面积小,耕地质量差,仍是全国重要的农产品生产基地之一;各省(区)土地利用状况各具特色,可利用潜力较大;近年来西北地区肥料用量增长减缓,单质氮、磷肥基本稳定,钾肥和复合肥在增加;各省(区)施用肥料的结构以氮肥为主,复合肥次之,钾肥比例很低;单位种植面积施肥量低于全国水平;西北地区主要作物施肥量差别很大,其中蔬菜、棉花施肥量最多,小麦、玉米居中,豆类、薯类和油料类较少。多年来化肥生产量一直低于消费量,但氮肥发展为供大于求。综合分析认为,作物生产用肥量尚有进一步增长的可能性,需进一步研究草地用肥的可能性。应注意土地合理利用、施肥效果、施肥量和草地施肥等问题。     

Orthogonal polynomial models to describe yield response of rice to nitrogen and phosphorus at different levels of soil fertility

Yield responses of rice (Oryza sativa L. cv JD1187)to variable rates and combinations of fertilizer nitrogen (N) and phosphorus(P), to available soil N and P, and to cation exchange capacity (CEC) wereexamined in 41 field trials. The trial sites were located in the rice-growingregion of Hebei Province, Northern China, covering a diversity of soilfertilitylevels. Relationships between crop yields, fertilizer rates and soil nutrientsupply were established using an orthogonal polynomial model. The optimumeconomic fertilizer rates at different levels of soil N and P supply wereestimated by using fertilizer-yield response functions and soil properties foraparticular site. A difference in trend coefficients, reflecting yield responseto fertilizer, was observed, which was mainly dependent on variance of soilfertility across 41 experimental sites under the relatively consistent climateand farming practice. The results of correlation analysis showed that there wasa positive correlation between trend coefficient T₀ and yieldwithoutfertilizer (Y₀) (r = 0.80**). Trend coefficientT₁, the major effect of N fertilizer on yield, showed negativerelationships with the quadratic transformation of alkali-hydrolysable N(N_s) and CEC (r = –0.60**). Trend coefficientT₂, the major effect of P fertilizer on yield, had negativerelationships with the logarithmically transformed data of soilNaHCO₃-extractable P (P_s) (r = –0.57**).Trend coefficients T₃, T₄ and T₅, representinglinear interaction of N and P, and quadratic trend of N and P, respectively,showed no significant correlation with soil fertility variables. Yieldresponsesto N and P fertilizers, optimum economic fertilizer rates and gross profit fromfertilization decreased with increase in available soil N and P, and CEC. Themodel was validated in 19 field trials. The results suggest that the modeldeveloped in this study can reasonably predict optimum economic fertilizerratesthrough routine soil tests in the rice production region. The model can also beextrapolated to other regions and include other variable factors, provided thatnew relationships between yield response to fertilizer and site variables areestablished and incorporated into the model.     

Major nutrient balances in small-scale vegetable farming systems in peri-urban areas in China

Balances of major nutrients such as nitrogen (N), phosphorus (P), and potassium (K) in small-scale farming systems are of critical importance to nutrient management and sustainable agricultural development. Mass balances of N, P, and K and some of their influencing factors were studied for two years from July 2003 to July 2005 on small-scale vegetable-farming systems in two contrasting peri-urban areas (Nanjing and Wuxi) of the Yangtze river delta region of China. This balance approach considered organic fertilizer inputs (cow manure, pig manure, and human biosolids), inorganic fertilizer inputs (urea, composite fertilizer, and phosphates), irrigation water, and atmospheric deposition; and considered outputs by vegetables. Input via organic fertilizers was significant for all element balances in the Nanjing area. Inorganic and organic fertilizer, particularly inorganic fertilizer, contributed major nutrient inputs to the system in the Wuxi area. Compared with nutrient output by vegetables, there were significant surpluses of N and P on two vegetable farm systems. Furthermore, N surplus in the Nanjing area was higher than that in the Wuxi area with an inverse relationship to P surplus. In contrast, the general trend of K balances was negative on both sites; hence, the nutrient use efficiency was significantly lower for N and P than K. The nutrient imbalance may be attributed to the differences between fertilizer types and management modes driven by social economic status differences among farmer households. The large N and P net excess creates an environmental threat because of potential losses to ground or surface waters, whereas negative K balance creates soil fertility risks. The results highlight researchers’ and farmers’ need to develop rational fertilization technology to optimize nutrient management on vegetable farmlands to promote sustainable agricultural development in peri-urban areas.     

Nutrient recycling potential in rice–vegetable cropping sequences under in situ residue management at mid-altitude subtropical Meghalaya

Low native soil nitrogen (N) and very low phosphorus (P) coupled with apathy of farmers towards use of fertilizer are the major constraints limiting rice productivity in the North Eastern Hill (NEH) Region of India. Field experiment was undertaken in narrow valley wetland during Kharif and pre-Kharif (rainy) seasons of 2003, 2004, and 2005, respectively, at Umiam (950 m MSL), Meghalaya to evaluate the nutrient recycling and production potential of rice (Oryza sativa L.)—vegetables cropping sequences under low input in situ residue management under rainfed conditions. After rice, five vegetable crops, viz. tomato (Lycopersicon esculentum Mill), potato (Solanum tuberosum L.), frenchbean (Phaseolus vulgaris), cabbage (Brassica oleracea L. var. capitata), and carrot (Daucas carota L.) were grown during pre-kharif season on temporary raised and sunken beds. Minimum tillage was given to both rice and vegetables. No external input including fertilizer, organic manure, pesticides, etc. were applied to either crops. Only the economic parts of the crops were harvested and the rest of the biomass of the entire crop and weed residues were chopped and incorporated into the soil. Among the five cropping sequences, rice–tomato gave the highest rice equivalent yield (214.40 q/ha), followed by rice–carrot (206.4 q/ha). Highest net return (rupees [Rs.] 66,635 ha⁻¹) was recorded in rice–carrot, closely followed by rice–tomato (Rs. 66,139 ha⁻¹). Rice–cabbage and rice–frenchbean were found to be on a par with each other in terms of yield and income. The highest amount of NPK recycling was recorded for the rice–potato sequence. Weed biomass production in the different sequences ranged from 37.5 q/ha for rice–tomato to as high as 50.6 q/ha in the case of rice–fallow. Soil fertility in terms of available NPK status was found to be stable in all the crop sequences except rice–cabbage, where fertility status declined slightly. The soil biological properties such as population of Rhizobium, bacteria, phosphorus-solubilizing microorganisms, and earthworm activity were all found to be remarkably higher in the experimental field compared to other adjacent plots that are managed inorganically. It was concluded that vegetables such as tomato, carrot, potato, etc. could be profitably grown after rice without the addition of fertilizer and manure, if residues are managed effectively under temporary raised beds without deteriorating soil fertility.     

农业经济增长与化肥投入关系研究

以重庆市1996-2010年的数据为基础,构建库兹涅茨曲线来验证化肥投入强度与农业经济增长的关系,并对农业经济增长过程中化肥投入强度的演变趋势进行了定性与定量分析.研究结果表明,农业经济增长与化肥投入强度之间存在显著的库兹涅茨曲线关系,转折点发生在2009年.提出加强测土配方施肥技术推广,引导、鼓励农民科学施肥,加大农村环境保护宣传力度,提高农民的文明素质等对策建议.     

Phosphorus,Potassium and Leucaena Pruning Interactions on Corn in Haiti

Few P and K fertility studies have been conducted on Haitian soils. Alley cropping is promoted in Haiti but has not been studied in relation to P and K fertility. The effects of P and K fertilizer and leucaena (Leucaena leucocephala (Lam) De Witt) pruning mulch applications on corn (Zea mays L.) were assessed in field experiments on Rhodudalfs over limestone at Salagnac, Lithic Hapludolls over limestone at Bergeau and Typic Hapludalfs over basalt at St. Georges, Haiti. Complete block designs arranged in incomplete factorials of P and K rates were carried out during three seasons. Additional treatments consisted of 30 Mg ha⁻¹ of leucaena prunings applied with and without 60 kg P and 40 kg K ha⁻¹. Grain yield and net income were analyzed and a surface response curve was fitted on treatments without pruning applications. The soils differed markedly in response to P and K with significant PXK interactions. Without leucaena prunings, response surface analysis predicted maximum yields with applications of 95–117 kg P ha⁻¹ and 51–72 kg K ha⁻¹ and maximum net returns with applications of 0.22–89 kg P ha⁻¹ and 43–79 kg K ha⁻¹. Leucaena pruning applications increased yield at all sites. Highest net income was obtained at Salagnac and St. Georges with leucaena prunings applied with P and K, at Bergeau with prunings applied without P and K, suggesting that alley cropping with judicial fertilizer use is a good economic alternative for low resource farmers. Soil parent material and mineralogy should be considered in making fertilizer recommendations.     

Relative time‐averaged gain array (RTAGA) for distributed control‐oriented network decomposition

Input‐output partitioning for decentralized control has been studied extensively using various methods, including those based on relative gains and those based on relative degrees and sensitivities. These two concepts are characterizations of long‐time and short‐time input‐output response, respectively. A unifying new input‐output interaction measure, called relative time‐averaged gain, which characterizes the input‐output interactions during a time scale of interest for linear time‐invariant systems is proposed. This measure is used as a basis for community detection in the input‐output bipartite graph of a process network to produce subnetworks whose responses are weakly coupled in the time scale of interest. As such, the resulting decomposition accounts for both response characteristics and the network topology, and can be used efficiently for distributed control architecture design. In a case study, the proposed decomposition is applied to the distributed model predictive control of a reactor‐separator benchmark process. © 2018 American Institute of Chemical Engineers AIChE J, 64: 1682–1690, 2018     

Provincial potassium balance of farmland in China between 1980 and 2010

Great changes have been happened over the past 30 years in chemical fertilizer input in China, and thus a gross potassium (K) budget model established to evaluate the variation of farmland K balance for China in 1980 and 2010 at the national scale is important. Results indicated that total K input in 1980 was 6.8 million tonnes, in which chemical fertilizer, organic manure and other sources accounted for 5.6, 77.5 and 16.9% respectively. Total K input in 2010 was 21.6 million tonnes, in which chemical fertilizer, organic manure and other sources accounted for 43.5, 50.4 and 6.1% respectively. Total K output in 1980 was 8.1 million tonnes, in which crops removal and loss accounted for 98.2 and 1.8% respectively. Total K output in 2010 was 19.1 million tonnes, in which crops removal and loss accounted for 99.2 and 0.8%, respectively. Similar to K input, the spatial distribution of K output differed greatly. Total K deficit was 1.3 million tonnes, and the range of K balance in each province was ?86.7 to 53.6 kg K₂O ha^?1 in 1980. Compared with that, total K surplus was 2.5 million tonnes and the range of K balance in each province was ?43.0 to 256.6 kg K₂O ha^?1 in 2010. Chemical fertilizer K application over the past 30 years makes the great changes in average K balance from deficit to surplus in general; however, the great spatial variation in K balance drives urgent need for site-specific K nutrient management.     

Artificial neural networks for colour prediction in leather dyeing on the basis of a tristimulus system

Computer‐assisted colour prediction and quality control have become increasingly important to the dyeing process in many consumer goods manufacturing industries, including textile and leather. The most challenging aspect concerns dye recipe prediction for the production of the required shade on a given substrate. Computer recipe prediction based on the conventional and widely used Kubelka–Munk model often fails under a variety of conditions. In the present investigation, an attempt has been made to develop an artificial neural network model to predict colour in terms of tristimulus values (X, Y, Z) given the concentration of dyes. An artificial neural network model was trained with 300 pairs of known input vectors, i.e. dye concentrations, and output vectors, i.e. colour parameters, using a backpropagation algorithm. The artificial neural network topology consists of three neurons in the input layer to represent the concentration of dyes, three neurons in the output layer to represent the tristimulus values X, Y, and Z, and five neurons in the hidden layer with a log‐sigmoid transfer function. The artificial neural network results showed a good level of colour prediction during the training and testing phase. The results also indicate that the artificial neural network has the potential to give better predictive performance than the conventional Kubelka–Munk model.     

论提高我国化肥利用率

对比世界各国人均耕地、人均施肥量、人均谷物产量及消费量等农业基础数据,认为：我国人多地少,人均耕地０．１１４ｈｍ２（与英、德国家相近）;土壤总体肥力较低,必须靠增施化肥来提高单产,因而化肥需求量将持续增长;但增加化肥产量近期受投资及能源产量的制约、远期受二氧化碳排放量及水体污染的制约;我国化肥施用总量占世界第一位,但在销售、供应和施用方面还存在不少问题。指出应把研究提高化肥利用率作为降低农业生产成本的一项长期的主要措施,最后对开源节流提高我国化肥利用率提出若干建议。     

磷的农业化学（Ⅴ）

根据土壤供肥性能、作物需肥特性和肥料效应,提出推荐施肥建议（或称平衡配方施肥）。其计算方法一般分为三大类,即地力分级分区配方法、目标产量配方法、肥料效应函数法。各种方法均有其优缺点,可因地制宜选用。化肥对粮食产量的增产率为５０％ 左右,但化肥费用占农业生产成本的２５％ 以上,占全部物资费用的５０％ 左右,必须对化肥的投入产出效果加以研究和优化,尽量选择经济最佳的施肥量。环境问题,已成为当今世界实行可持续发展战略中的重要议题。必须十分重视磷肥对水体富营养化,和磷肥中的氟、重金属、放射性元素、镉等对土壤的污染