Enhancing Agricultural Productivity for Health & Environment

1. Quality inputs and plant nutrition: implications for human health and the environmentQuality of agricultural inputs: Managing nutrition and health of plant, people and environment AGELE Samuel, PhD Department of Crop, Soil & Pest Management, Federal University of Technology, Akure, Nigeria *Visiting Professor & Dean, Faculty of Agriculture, University of Africa, Toru-Orua, Bayelsa State, Nigeria Tel:+2348035784761: Email: soagele@futa.edu.ng: ohiagele@yahoo.com

2. PRESENTATION HIGHLIGHTSQuality of agricultural inputs: Managing nutrition and health of plant, people and environment Improving access to high-quality agricultural inputs and services is key to increasing agricultural productivity to address food and nutrition security challenges and healthy/sound environment. The relevance of quality agricultural inputs for managing plant and human nutrition and health of the total environment underscored the need for ensuring quality seeds, fertilizers, insecticides and other agricultural inputs to farmers to boost yield and quality of crops and get fair prices. Current advances in plant mineral nutrition aim at developing appropriate agronomy, improved crop genotypes, and more efficient use of quality inputs (especially fertilizers inorganic and organic fertilizers). In developing country agriculture, knowledge should be strengthened and best management practices (BMP) developed for adoption in order to produce agricultural products with sufficient mineral elements for enhanced plant and human nutrition, whilst limiting the entry of toxic elements to the human food chain and thus, the ecosystem. The presentation will highlight current understanding of how agricultural production inputs affect soil, crop and human nutrition and therefore the total ecosystem health, and thus, the role of knowledge/innovation/technologies/practices from soil science, agronomy, plant physiology, and crop genetics in delivering sufficient, safe, and nutritious food to meet the dietary needs of an increasing human population, and the conservation of the quality of the environment.

3. Table of Contents • Summary of the Presentation • Agricultural inputs • Risks of poor quality inputs • Addressing challenges along input activities • Fertilizer management for optimal production • Fertilizer use efficiencies • Nutrient use efficiencies from applied fertilizers • Nutrient use and food production • Fertilizer use and food production: A global perspective • Ecologically sound fertilizer management • Precision agriculture and fertilizers • Food security situation and food supply capacity of SSA • Soil, Fertilizer and Pant Analysis • Discussion, Comments, conclusions and recommendations

4. SUMMARY Improving access to high-quality agricultural inputs and services is key to increasing agricultural productivity and address food and nutrition security and environment health challenges. Mineral malnutrition affects two-thirds of the world's population. Appropriate agronomic practices, improved crop genotypes, and more efficient use of inputs (especially fertilizers inorganic and organic fertilizers) should be developed to plant mineral nutrition Mineral malnutrition affects two-thirds of the world's population. Mineral malnutrition challenge should be addressed via application of fertilizers, soil amelioration, and improved crop genotypes that accumulate safe concentrations of mineral elements in their edible tissues This will boost human nutrition (diets) whilst limiting the entry of toxic elements to the human food chain and thus, the ecosystem. Excessive concentrations of harmful mineral elements compromise crop production, human and ecosystem health. The entry of toxic elements into the food chain should be restricted Quality requirements for agro-input usage enforced, agronomic strategies employed to increase efficiencies of input use

5. SUMMARY The relevance of quality agricultural inputs for managing plant and human nutrition and health of the total environment underscored the need for ensuring quality seeds, fertilizers, insecticides and other agricultural inputs to the farmers to boost yield and quality of crops and get fair prices. Also required, are development of best management practices (BMP) for soil, fertilizer use and crop for enhanced plant and human nutrition and attainment of current and future food and nutrition security, and healthy ecosystems. The presentation will highlight current understanding of how agricultural production inputs affect soil, crop and human nutrition and therefore the total ecosystem health, and thus, the role of knowledge/innovation/technologies from soil science, agronomy, plant physiology, and crop genetics in delivering sufficient, safe, and nutritious food to meet the dietary needs of an increasing human population, and the conservation of the quality of the environment.

6. Agricultural Inputs External crop production inputs are: mineral fertilizers, organic amendments, microbial inoculants and pesticides which are applied with the ultimate goal of maximizing productivity and economic returns, while side effects on soil and ecosystem health are often neglected. The quality of agricultural inputs affects soil, crop and human health External production inputs are: fertilizers, organic manure, microbial inoculants and pesticides They are applied to maximize productivity, quality and economic returns, Sound management of agricultural production inputs must attempt to ensure enhanced product quality and safeguarded environment. The option of Integrated Nutrient Management (INM) strategy and user-friendly protocols must be strengthened and adoption by farmers encouraged.

7. Agricultural Inputs Agricultural inputs are defined as products permitted for use in agriculture. Agricultural inputs include feedstuffs, fertilizers and permitted plant protection products as well as cleaning agents and additives used in food production. List of Agricultural inputs : 1. In organic fertilizers , 2.Pesticides which includes insecticides, fungicides, nematicide and herbicide 3. Vegetative propagated planting materials , 4. Bio pesticide , 5. Plant growth regulators 6. Micro nutrients , 7. Bio control agents, microbial inoculants, 8. Animal feeds , 9. Poultry feeds, and 10.Farm machinery and agricultural tools.

8. Risk of poor quality inputs In SSA where less than 10 % of smallholder farmers use inorganic fertilizers, the majority of fertilizers available are of substandard quality and that very few of the available improved , hybrid seeds of most crops would not end up increasing yields likely due to ‘fake’ or poor-quality inputs. Farmers often times complain about low quality fertilizers and other agro-inputs. Reports across Africa have shown that modern agricultural inputs like improved seeds and fertilizers have the potential to improve yields. However, in practice, the prevalence of poor-quality or counterfeit seeds and other inputs in the market can make it inadvisable for small-scale farmers to take the risk of purchasing inputs that only promise higher yields. Most times, farmers rely on seeds from their own harvest, resulting in substantially lower yields. Further work is needed to identify where quality deterioration happens along supply chains – whether during the initial production process or later through poor storage or counterfeiting – and how it can be stopped.

9. Quote for Alliance for Green Revolution in Agriculture (AGRA) In sub-Saharan Africa, inadequate quality inputs is a key reason yields on many farms in the region are low—the amounts of maize, banana, and other crops harvested per hectare or acre—are far below yields achieved in other developing countries When African farmers have access to the same basic agricultural inputs farmers around the world take for granted, their harvests quickly double or triple. A major barrier to agricultural development in sub-Saharan Africa is the low quality of many agricultural inputs – coupled with a lack of reliable information on input quality. The risk of poor quality inputs poses a major constraint to agricultural development as input quality is often hard for farmers to detect. The Swedish Research Council , FAO, AGRA have reported that in SSA, farmers may be wise not to invest in some inputs, given their widespread poor quality.

10. Risk of poor quality inputs Various studies have evaluated the quality of fertilizers (samples should be sent to laboratory to determine its chemical composition) and seeds on test plots For example, yields obtained have shown that the so-called improved hybrid seed bags bought from local retailers seemed to be diluted with only half the seeds being hybrid (the other half were traditional seeds). Urea fertilizer – the most common type on the market has been found to have 33% less nitrogen content than advertised. These reports are indicators of the magnitude of the problem of poor quality agricultural inputs. The findings highlight the need for improved information on input quality standards and appropriate use of inputs, and improved monitoring and enforcement of agricultural input standards. Farmers have obtained negative return on their investments from fertilizers or improved/hybrid seeds in contrast to the expected high returns (yielded average returns above 50%)

11. Risk of poor quality inputs It is imperative to restore farmers’ trust that agricultural inputs, products and technologies agricultural inputs should meet quality standards via the establishment of reputable brands or more reliable and transparent ways of testing quality. It is worth noting that many challenges exist in ensuring food safety on the consumer side. Consumers are unable to observe many important quality and safety characteristics when purchasing food, similar to the challenge that farmers face when they buy inputs. Inadequate crop and food regulation can have adverse effects on consumers health by allowing food with toxins or insufficient nutrition elements to enter markets. Consumers value information on food origin, taste, and safety and such information can help resolve and build confidence along agricultural production and food supplies.

12. Risk of poor quality inputs Agricultural inputs producers, suppliers, businessmen, and other service providers would have to be sincere and honest in supplying and selling good quality inputs (seeds, fertilizers, insecticides and other inputs) to farmers so that growers are not cheated. This calls for strong linkage between farmers and input producers and suppliers, strengthening of monitoring system and supervision by the officials of department of agriculture extension (DAE) DAEs to check the sale of adulterated and fake seed, fertilizers and pesticides and other inputs to the farmers. Government should educate, create and improve awareness of farmers on the relevance and application of available state-of-the-art innovations, practices and technologies developed by agricultural scientists, and provide need-based training aimed at producing quality crops for human nutrition and ecosystem health.

14. Addressing challenges along agricultural input activities Availability, access and usage of high quality agricultural inputs by farmers improve Efforts should be geared towards decreasing the prevalence of counterfeit and poor agricultural inputs in the markets. Proposed are: Anti-counterfeit campaign must be strengthened e-verification: to provide electronic assurance to consumers that they have purchased genuine products. Support for national education campaign to increase farmers’ understanding of good service delivery, and demand for verification of the quality of inputs. Ensure the availability of high quality seed by consortium of seed companies utilizing internationally accredited seed certification services. Support for emergence of a private sector seed certification service and seed company inspectors. The National Seed Certification Agency should recognize the role of the private sector in seed certification and to delegate inspection authority

15. Addressing the challenges along agricultural input activities Professionalisation of agro-chemical supply: To improve market of safe and environmentally responsible agro-pesticide/fertilizer supply and usage (ensuring judicious and effective use of agrochemicals, Need for training and re-training of agro dealers for safe and responsible service delivery,and facilitate the revision of the training curriculum and the guidelines for agro-dealer licensing to sell chemicals. Compliance: Improvement of regulatory environment , and agro-dealers to legally register and be licensed The Registration Services, Standard Organization of Nigeria (SON), local governments and the Ministry of Agriculture to try to facilitate a coordinated effort Agricultural input businesses should adopt customer service business strategies Access to finance: Availability of appropriate financing for agricultural inputs Distribution: Establish efficient, defined and effective distribution channels that are equitable, and traceability, backed by consumer confidence. Interventions to adopt use of e-voucher systems for government distribution programmes

16. FERTILIZER MANAGEMENT FOR OPTIMAL PRODUCTIVITY AND SUSTAINABILITY Sustainable crop production is achieved when stable levels of food production and quality are maintained without compromising economic profitability or human and environment health. Crops require a sufficient, but not excessive, supply of essential mineral elements for optimal productivity. An insufficient supply of mineral elements required in large quantities and/or those with low phytoavailability in soils often limits productivity and quality. In many agricultural soils, there is rarely sufficient phytoavailable N, P or K to supply enough of these elements for the rapid growth of crops during their early growth. Hence, these elements are supplied as fertilizers in both intensive and extensive agricultural systems. Fertilizers are applied not only to increase crop yields, but also to increase concentrations of essential mineral elements in edible portions of plants and the residues. However, there are both financial and environmental costs to the use of mineral fertilizers (Galloway et al., 2008; Ju et al., 2009). It is therefore important to optimize the efficiency with which fertilizers are used to safeguard plant, human and environment health

17. Fertilizer use efficiencies Increased fertilizer use efficiency can be achieved agronomically through improved fertilizer-management practices, and/or genetically, by cultivating crops that acquire and/or utilize mineral elements more effectively (Agele et al., 2008, 2011, FAO 2015). Agronomic mineral use efficiency (MUE) is generally defined as crop dry matter (DM) yield per unit of mineral element available (Ma) in the soil (g DM g−1 Ma). Agronomic mineral use efficiency is equivalent to the product of the plant mineral content (Mp) per unit of available mineral (g Mp g−1 Ma) This is often referred to as plant mineral uptake efficiency (MUpE), while Yield per unit plant mineral content (g DM g−1 Mp), is referred to as the mineral utilization efficiency (MUtE). NUE is a complex genetic trait comprising N uptake and N utilization. N uptake efficiency (NUpE) is the ability of the plant to take up N from the soil. N utilization efficiency (NUtE) is the ability of the plant to assimilate and remobilize the N taken up from the soil, producing amino acids to be used as N carriers or signalling and regulatory pathway components and ultimately to produce grain (Moll et al., 1982; Moose and Below, 2009). It has been proposed that breeding crops that acquire and/or utilize nutrients more effectively can reduce the amount and environment costs of fertilizer use in agriculture NUE of cereals is estimated to be 42 % and 29 % under different management practices and climate (Hodge et al., 2000).

18. Fertilizer use efficiencies Under-use of N fertilizers is costly to subsistence farmers who rely on their crops to yield enough food to feed their family nutritiously. Therefore, some areas of the world need to focus on reducing N fertilizer use, while other areas need to have greater access to N fertilizers. Coupled to the rate of N fertilizer application is the inherent low nitrogen-use efficiency (NUE) of crops. The need to increase nutrient use efficiency (NUE) from applied fertilizers by either N management strategies, traditional plant breeding methods or biotechnology cannot be over stressed This will enhance economic benefits of the farmer (producer), consumer and the environment Considerable within-species genetic variation has been observed in all these measures for the mineral elements frequently supplied in fertilizers, including N, P and K The nutrient use efficiency (NUE) from applied fertilizers by crops can be determined under low and high fertilizer rates ( efficiencies of uptake (NUpE), utilization (NUtE) and coversion into issue biomass, OR Via monitoring of tissue amino acid profiles in genotypes, which might be related to their NUtE.

19. Nutrient use efficiencies from applied fertilizers Mineral nutrient use efficiency(NUE) are known to be under genetic and physiological control Determining trait(s) or gene(s) which control NUE in species/varieties is important Genotype-based NUE characteristics help pinpoint genetic targets for improving crop NUE. Estimates of overall efficiency of applied fertilizer : about 50% for N, less than 10% for P, and about 40% for K. Plants that are efficient in absorption and utilization of nutrients greatly enhance the efficiency of applied fertilizers, reducing cost of inputs, and preventing losses of nutrients to ecosystems.

20. Nutrient use efficiencies from applied fertilizers Nitrogen (N) is an essential element for both crop development and yield. However, since the green revolution, 50 years ago, farmers tend to maximize N fertilizer usage to maximize crop yield and quality As the need for more food production increases, the global consumption of synthetic (commercial) fertilizers and organic (manure) has increased Globally there has been an increase in N fertilizer use, this is not uniform in all countries or geographic areas (Vitousek et al., 2009). Many agricultural soils of the world are deficient in one or more of the essential nutrients needed to support healthy plants. Some areas, such as North America, have steady increases in N fertilizer use, China is showing a substantial increase in use, while Denmark has a reduction in use and Africa has a chronic under-use of N fertilizers (Mosier et al., 2004, Agele et al., 2008).

21. Fertilizer use and food production: A global perspective There are several costs associated with both over and under-use of N fertilizers that are borne by all. High N-fertilizer consumption is also environmentally damaging, with excess N lost by leaching into groundwater and runoff into surface water, plus ammonia volatization and production of NOx gases from denitrification polluting the atmosphere (Agele et al., 2004, Galloway et al., 2008; Conley et al., 2009). Current production systems for crops, meat, dairy and bioenergy rely strongly on the external input on minerals from fertilizers (N, P and K) including micronutrients. It is necessary to identify key features of the relationships between fertilizer use, plant and human nutrition in order to develop sustainable options for improved fertilizer (nutrient) us efficiency, , less N-polluting and secure agriculture and food system. Fertilizer use in agriculture has enhanced productivity per unit of land, however, the drawback is a complex web of pollution problems contributing in a major way to degradation of ecosystems.

22. Fertilizer use and food production: A global perspective Farmers in sub-Saharan Africa could increase their production considerably if they had access to fertilizer and the technology to use it appropriately: the limitation is probably poverty. In much of the world there is scope to increase fertilizer application per hectare by 50 % which has produced significant yield gains In future, as yields rise, so will nutrient off-takes, and these off-takes will need to be taken care of if agriculture is to be sustainable. Some crops leave a large proportion of the soil-applied fertilizer in the soil at the end of the growing season, where it represents a waste of resource to the farmer and a pollutant to water and/or air. More efficient ways to apply fertilizers will be needed so that it does not get left in the soil, where it is prone to leaching and a cause of water pollution. Plant breeders and agronomists have engaged in research for ways to improve uptake and N use efficiencies.

23. Ecologically Sound fertilizer management Ecologically sound fertilizer management strategies for field crop production may rely more on precision placement of fertilizer for optimizing soil, plant and human nutrition and health Research reports have highlighted the importance of the early nutrition of vegetable crops, and its long-term effects on their subsequent growth and development and human nutrition and health. Reports demonstrated how the nutrient supply during the establishment stages of young seedlings and transplants can be enhanced by targeting fertilizer to a zone close to their developing roots. Some precision fertilizer placement techniques are: starter, band or side-injected fertilizer. The methods have produced the same (or greater) yields at lower application rates than those from conventional broadcast applications, increased recovery of N, P and K, and Overall efficiency of nutrient use, while reducing the levels of residual nutrients in the soil.

24. Precision agriculture and soil/fertilizer management practices Starter fertilizers also advanced the maturity of some crops, and enhanced produce quality by increasing the proportions of the larger and/or more desirable marketable grades. Precision agriculture is a technology and information-based system used to manage farm inputs and spatial and temporal variability in productivity thus maximize sustainability, profitability, and environmental safety (McBratney et al., 2005). In agriculture, soil fertility and plant nutrition can be managed through precision farming methods using modern technological approaches and sensors. Local or remote N sensors could be helpful in sophisticated management practices to assess plant needs for supplemental nutrient. Several soil-crop simulation models are available, and have paved the way for effective fertilizer management These models integrate the effect of soil, weather, cultivar, pest, and other management practices on the growth and yield of crop.

25. Precision agriculture and soil/fertilizer management practices Site-specific nutrient recommendations can be made through the use of geographic information system (GIS) and global positioning system (GPS). Remote sensing tools such as satellite imagery, ground-based optical sensors, ground-based reflective sensors, aerial imagery, and leaf chlorophyll sensors (Sharma and Bali, 2017). In agriculture, remote sensing has been in use since long for estimating land cover, land use, and crop biomass, and it has now been utilized to estimate the spatial crop N status in season (Henebry et al., 2005). Under precision agriculture, soil testing approach prior to crop planting, in-season nutrient management based on sensors, and split application of fertilizers are viable options for improving efficiency of nutrient usage in agriculture Under precision agriculture, soil testing approach prior to crop planting, in-season nutrient management based on sensors, and split application of fertilizers are viable options for improving efficiency of nutrient usage in agriculture

26. PLANT NUTRITION FOR HUMAN HEALTH How knowledge of plant mineral nutrition is contributing to sustainable crop production and human health. Plants require at least 14 mineral elements for their nutrition. These include the macronutrients nitrogen (N), phosphorus (P), potassium (K), calcium (Ca), magnesium (Mg) and sulphur (S) and the micronutrients chlorine (Cl), boron (B), iron (Fe), manganese (Mn), copper (Cu), zinc (Zn), nickel (Ni) and molybdenum (Mo) Humans are likely to require at least 25 mineral elements for their well-being (Stein, 2010). The dietary source of most of these elements is plants. Regrettably, mineral malnutrition is prevalent world wide This is considered to be one of the most serious challenges to humankind (Copenhagen Consensus 2008: http://www.copenhagenconsensus.com). It is estimated that up to two-thirds of the world's population might be at risk of deficiency in one or more essential mineral element (White and Broadley, 2009; Stein, 2010).

27. PLANT NUTRITION FOR HUMAN HEALTH The mineral elements most commonly lacking in human diets are Fe, Zn, I, Se, Ca, Mg and Cu (White and Broadley, 2009; Stein, 2010). Edible plant tissues can contain low concentrations of mineral elements for a variety of reasons: some plant species have inherently low concentrations of particular mineral elements. Some crop species have inherently low concentrations of Ca and Mg (Broadleyet al., 2004; Watanabe et al., 2007); For Se in soils derived mostly from igneous rocks (Broadleyet al., 2007); or edible portions could be consumed that have intrinsically low concentrations of mineral elements with restricted phloem mobility, such as fruits, seeds and tubers (White and Broadley, 2009). To address the occurrence of mineral deficiencies in human populations, agricultural scientists are devising methods of applying fertilizers and/or using plant breeding strategies to increase the concentrations and/or bioavailability of mineral elements in agricultural produce (Graham et al., 2007; White and Broadley, 2009).

28. PLANT NUTRITION FOR HUMAN HEALTH These approaches are termed ‘agronomic’ and ‘genetic’ biofortification of of edible crops with Fe and Zn The approaches have been of practical benefits for food production, economic sustainability and human and envirpnment health (Graham et al., 2007; White and Broadley, 2009). The successful use of inorganic Se fertilizers to increase dietary Se intakes in Finland, New Zealand and elsewhere (Ekholmet al., 2007), and the iodinization of irrigation water to increase dietary intakes of in China (Lyons et al., 2004). Researchers are investigating genetic variation in mineral concentrations in edible portions of major crops, the interactions between genotype and environment, and the potential for breeding for increased concentrations of mineral elements in produce (Cakmak, 2008; White and Broadley, 2009). In summary, enhanced knowledge of plant mineral nutrition has contributed to sustainable crop production, crop and human nutrition and health and soundness of the total environment

29. PLANT NUTRITION FOR HUMAN HEALTH Crop production is often limited by low phytoavailability of essential mineral elements and/or the presence of excessive concentrations of potentially toxic mineral elements in the soil and crop tissues. This can be addressed partially by traditional agronomic strategies and through the development of novel crop genotypes. Research has focused on breeding strategies by identifying traits and genes that can increase yields on soils with restricted phytoavailablity of essential mineral elements and soils compromised by excessive concentrations of mineral elements. The concentrations of mineral elements in edible plant tissues are therefore of fundamental importance to human nutrition. The essential mineral elements required by humans and other animals enter the food chain primarily through plants. It is estimated that up to two-thirds of the world's population might be at risk of deficiency in one or more essential mineral element, with deficiencies of Fe and Zn being most common (White and Broadley, 2009; Stein, 2010).

30. PLANT NUTRITION FOR HUMAN HEALTH The concentrations of mineral elements in edible crops can be increased by the judicious application of mineral fertilizers and/or by cultivating genotypes with higher concentrations. The bioavailability of mineral elements can also be increased through crop husbandry, breeding or genetic manipulation (White and Broadley, 2009). Reports have shown that the increasing population and limitations in cultivated land, low input use and use efficiencies, and poor soil, fertility and water resources management will strain food and nutrition security in SSA. A primary requirement for the future is to produce higher yields and quality products with inputs that do not lead to environmental problems either on- or off-site. Ideally nutrient additions (whether as mineral fertilizers or manures) and soil biota should be managed to deliver nutrients to crops synchronously with demand Much remains to be done in SSA to address these challenges and achieve improved plant and human nutrition , in addition to sustainable environment.

31. Food Security Situation and Food Supply Capacity of Sub-Saharan Africa (SSA). By 2050, the world population is likely to be 9.1 billion, in the circumstance, agriculture has to provide solutions to feeding the world There is a large gap between achievable yields and those delivered by farmers, even in the most efficient agricultural systems. In addition, it is estimated that by 2050, the enlarged world population with have changed dietary requirements of about 50 % , FAO's World Expert Forum had raised this estimate to 70 %. This poses a considerable challenge: how to increase yield while simultaneously reducing energy consumption (allied to greenhouse gas emissions) and utilizing resources such as water and fertilizers more efficiently. Given the timeframe in which the increased production has to be realized, most of the increase have to come from crop genotypes together with known agronomic and sound management practices that are currently not developed. With the human population of Sub-Saharan Africa expected to double and food demand to triple over the next 50 years, decisions made today can have profound effects on the future. Achieving ‘zero hunger’ and addressing mineral mal-nutrition in sub-Saharan Africa whilst reducing environment quality degradation has perhaps never been more critical.

32. Soil, Fertilizer and Plant Analysis Interpretation and Application of Soil/Plant Analysis Results to Attain Optimum Crop Yields, Quality and Sustainable Environment.Soil and Plant Analysis has relevance for crop yield and quality increases Analysis of soil and plant is commonly referred to as the measurement of essential nutrients of soil samples and plant tissue using established laboratory procedures. The practice of plant analysis dates back to studies of plant ash content in the early 1800s, when chemists recognized relationships between yield and nutrient concentrations in plant tissues. Today, technology advances have brought soil and plant analysis and data interpretation to new heights, consequently, considerable numbers of laboratories in different countries now have the capability to perform the analyses of soil and plant samples.

33. Soil, Fertilizer and Plant Analysis A soil test is a chemical method for estimating the nutrient-supplying power of a soil. Although plant analyses are extremely valuable in diagnosing nutrient stress, analysis of the soil is essential for determining the supplemental nutrient requirements of a particular crop. Compared to plant analysis, the primary advantage of soil testing is its ability to determine the nutrient status of the soil before the crop is planted. However, soil tests are not able to predict the quantity of a nutrient taken up by a crop. To predict the nutrient needs of crops, soil test results must be calibrated against nutrient uptake and yield in field trials.   The results of soil analysis can provide very misleading information if the laboratory procedures are not carried out correctly. Therefore it is always prudent to submit check samples to verify that a particular laboratory is able to determine consistent values for key soil physical and chemical properties. Critical values for key soil parameters are rough guides for the need for fertilizer at best. For example, soil total N does not reveal much useful information about N availability to crops in a particular season but analysis of available P and exchangeable K can provide a good indication of whether the soil is able to supply sufficient quantities of these nutrients for crop growth.

34. The Relevance of Soil, Fertilizer and Plant Analysis Modern soil and plant analysis is used primarily as a source of information on plant nutrient status and, ultimately, as a tool to aid in nutrient management decisions. For nutrient management of crops, analytical data are used in various tests to : Diagnose existing nutrient problems Predict nutrient problems likely to affect crop production between sampling and harvest Monitor crop nutrient status for optimal crop production Environmental consequences of agricultural usage of agrochemicals (fertilizers and pesticides) Other, less common applications are: crop-quality measurements, regional nutrient status evaluations, assessment of crops for animal and human nutrition, and environmental protection.

35. Prediction of Nutrient Response Once the nutrient status of soil and plant tissue has been diagnosed, the information may be used to correct existing problems if time allows, or to help predict and prevent future problems. There are factors that affect nutrient dynamics from sampling to harvest, such as redistributable nutrient stores in the plant, nutrient supply capacity of the soil, and nutrient requirements for growth and yield. Plant analysis may provide information on only the first of these three factors. The most common method of using plant analysis for predicting response to nutrient application involves the setting of nutrient predictive standards in the same way as for diagnostic standards, but correlating nutrient concentrations with final, rather than current, yield. Where enough data have been collected and assimilated, recommendations for fertilizer (especially N) application from soil and plant analysis may be made by integration with other factors such as climatic risks and soil properties through the use of computer software and models.

36. Fig. 1. Relationship between nutrient concentration in plant tissue and yield or growth (Adapted from Marschner, 1995)

37. Plant Tissue Analysis and Interpretation (Crops : Arable and vegetables) Improved fertilizer management for crops is important in view of today's need to reduce production costs, conserve natural resources, and minimize possible negative environmental impacts. These goals can be achieved through optimum management of fertilizers in agriculture. Understanding the crop nutrient requirements and using soil testing to predict fertilizer needs are keys to sustainable fertilizer management. Plant tissue testing is another tool for use in achieving a high degree of precision in fertilizer management. Timely tissue testing can help diagnose suspected nutrient problems or can simply assist in learning more about fertilizer management efficiency. Guidelines should be provided for collecting samples, proper handling of the sample, and choosing an analytical lab assist growers (farmers), extension personnel, and consultants in conducting a meaningful plant tissue testing program. Information is also presented on basic plant nutrition so that the reader understands the nutrient requirements of each vegetable crop and the process of identifying nutrient deficiencies.

38. Some of the commonly used terms to describe levels of nutrient elements in plants include: :

39. Fertilizer Recommendation Fertilizer recommendations are based on the results of the soil test analyses and on the nutrient requirement of the crop to be grown. Recommendations on time and method of fertilizer application are also included. Each soil testing lab has its own philosophy for making fertilizer recommendations. Two examples are: 1. Recommendations which indicate the nutrient requirements and yield potentials for optimum economic production based one or more moisture conditions of the field. 2. "Target Yield Recommendations" which indicate the nutrient requirements for a range of various lower and higher yield potentials under the same moisture conditions. With this information the producers have the flexibility of selecting a fertilizer application rate or target yield that best suits their individual situation. Producers must keep in mind that optimum yields of high quality spring wheat can not be obtained without adequate fertilization if the crop to be grown on soils deficient in essential elements. Fertilizer application, however, will neither increase yield or quality of wheat if other management inputs and cultural practices are not optimal, nor will it increase yield if the added nutrients are not required. Therefore, the most successful fertilizer program will be based on a knowledge of soil nutrient status combined with optimum crop and fertilizer management practices.

41. Fig. . Relationship between nutrient concentration in plant tissue and top yield, showing the proposed critical nutrient range. (CNR). Source: Dow and Roberts, 1982

43. Plant Tissue Analysis Plant tissue analysis measures nutrient levelsin plant tissues during their growth. The supply of available nutrients is reflected in the nutrient content of the crop. Therefore use of plant tissue analysis allows a producer to evaluate the effectiveness of fertilizer recommendations from a soil testing service. Producers who do not soil test can still use routine plant tissue analysis to evaluate their fertilizer management program to determine whether they used the correct kinds and amounts of nutrient. Plant tissue analysis can be used to diagnose crop nutrition production problems. For example, at times, a plant growth problem occurs and can not be explained. Soil, climatic and other environmental conditions seem favourable, essential plant nutrients were supplied, and other sound management practices were followed, plant tissue analysis can indicate if nutrient levels may be associated with the problem. Hidden hunger is illustrated in Fig.

44. Fig. 3. Hidden Hunger is a term used to describe a plant that shows no obvious symptoms, yet the nutrient content is not sufficient to give the top profitable yield. fertilization with the "sure" rate rather than the bare economic optimum for an average year helps to obtain the top profitable yield. (Courtesy of the Potash & Phosphate Institute, Atlanta, Ga.) Source: Tisdale, et al., 1985

45. Table . Plant Tissue Analysis Interpretative Criteria : Crop Cereals Plant Part/Growth Stage Whole Plant Prior to Filling

46. Nutrient deficiency symptoms are often visible on crop plants.A healthy leaf (1), compared with N-deficient (2), P-deficient (3), K-deficient (4) and diseased (5) maize leaves. A young maize plant showing clear P deficiency symptoms

47. Nutrient deficiency symptoms are often visible on crop plants. Photo K deficiency symptoms in soyabean planted on K-deficient sandy soils derived from granite. Photo Multinutrient deficiencies may limit productivity in degraded soils. Here maize plants show Zn deficiency.

48. Nutrient Deficiency Symptoms For open field culture, the deficient nutrient can be top dressed over the crop or banded along side of the row if the crop is not too large. For most macronutrients (N, P, K, Ca, Mg, S), a side dressing of 30 to 40 lb. of element (P and K are in oxide form) per acre will correct a deficiency. Foliar applications of macronutrients (N, P, K, Ca, Mg, or S) are not recommended due to inherent inefficiency. Micronutrient (Mn, Cu, Fe Zn, B, and Mo) deficiencies can be corrected by application of small amounts of the deficient nutrient. Foliar application of the deficient micronutrient can be an effective means of correction if adequate leaf coverage is obtained. Micronutrients can be toxic in small amounts so care must be exercised to apply the recommended rates. For crops with waxy leaves, coverage can be improved by use of a spreader-sticker adjuvant in the spray tank.

49. Nutrient Deficiency Symptoms Plants exhibit deficiency symptoms that are characteristic for each element, and are, therefore useful for diagnostic purposes. However, in many cases, the symptoms may be masked by symptoms of other nutritional disorders, those caused by unfavorable environment, or stress caused by plant pests. In these situations, plant tissue analysis provides useful information to complement and confirm visual diagnosis. Nutritional disorders of vegetables rarely occur in well managed crops. The general symptoms associated with deficiencies and excesses of the essential elements follow: Nutrient deficiencies, if directly related to lack of fertilizer, must be corrected in timely fashion to avoid reduced yield and quality. It is best to avoid deficiencies by well executed soil-based nutrient programs, however, deficiencies if detected early enough can be corrected.

50. Discussions, Conclusions, Recommendations Take Home Message Comments, Observation