Preface   Most of us are aware that, there is a continuous decline in the productive potential of natural resources with time. With stepping up of industrial activities and growth in population & meeting its requirements, the per capita availability of land is also decreasing. This, in turn, has put up a challenge to produce more from less land. Therefore, protecting the available land resources from disruptive forces, such as, degradation, loss of fertility, nutrient imbalance, pollution, salinization, acidification, waterlogging etc. is now absolutely essential for future sustainability. Maintenance of adequate nutrient and water supply in soil is essential for plant growth and metabolism and sustain rich crop harvests. This will ensure food and nutritional security of the growing population and rural prosperity, besides bringing about a positive environmental change, peace and social harmony. What is difficult to understand is that, why such an important issue is not being addressed with the seriousness, that it deserves? Some of these concerns are: i) a gap of about 10 million tonnes of plant nutrients exists between the amount removed & the amount replenished at the current level of crop production, ii) about 47 million hectare of land under important cropping systems, have deficient available sulphur level, iii) over 30 to 40% area under cultivation in alluvial, black, red and calcareous soil regions have shown Zinc and Boron deficiency in cereals, pulses, oilseeds, vegetable and fruit crops, iv) crop yields in about 10 million hectares of the Indo-Gangetic Plains are plateauing, due to improper and imbalanced nutrient management practices. All these, call for an in-depth analysis, concrete plans and aggressive implementation, taking stake holders into confidence. This Book on ‘Plant Nutrient Disorders: Diagnosis and Management’ is the result of our thought process on the issues raised above. Authors feel that solution lies on a holistic and multi-faceted approach involving soil, water, plant, and environment and their surveillance system as an integral part of the management planning and practices for agricultural development. I am grateful to the authors involved in the preparation of different chapters in a strict time frame. Their invaluable contribution has been a major driving force in completing the assignment. I am indebted to my wife, Mrs. Sabita for her inspiring attitude, support, patience and encouragement in all such endeavours.

Soil is the most precious basic natural resource, on which depends the security of food, nutrition, income, biodiversity, livelihood and environment. But, its indiscriminate and unscientific management is a major threat to sustainability of agriculture. Over the years, there is a loss in the productive potential of soils, which is attributed to imbalance in nutrient use, mining of nutrients from soil, poor replenishment, loss of carbon, pollution, decrease in biological activities, waterlogging, soil salinity etc. Thus, land use is not commensurate with land capability.

Plant nutrient disorders result from nutrient imbalances in soils. Nutrients are considered essential for plants, when it satisfies the following criteria (Arnon and Stout,1939):     1.    The deficiency of the nutrient element makes it impossible for the plant to complete its life cycle     2.    The deficiency of the element is specific and can be corrected only by supply of that element     3.    The element is directly involved in the nutrition of the plant

Soils of India vary widely among different regions. The first soil map of India was prepared and classified on the basis of existing knowledge of Russian pedological principles. Govind Rajan (1971) and Govind Rajan and Rao Gopal (1978) have discussed in detail the later developments on the preparation of soil map of India and giving the equivalents of different soil groups in US Comprehensive System of Soil Classification. Soil resource mapping was initiated in 1986 and in a span of 10 years (1986-1996), a detailed database in terms of soils, their area and extent, characteristics and grouping following soil taxonomy (Soil Survey Staff, 1999) was created. The present chapter on “soils of India-nutrient status and management concerns” takes into account the following aspects:

A. Soil Sampling Soil is a store house of several nutrients. These are present in available and reserve forms and a dynamic equilibrium always exists between these forms of nutrients in soil. If the available form of a given nutrient element is depleted by crop uptake or by any other means, there will be immediate replenishment from the reserve source. In this context, it is also appropriate to note that soil is not an eternal source of plant nutrients. In a bid to produce more, soils are exploited very badly and they are gradually becoming deficient in several nutrients. There are several soil related constraints coming in the way of achieving sustainability in crop production.

Plant analysis includes tests on fresh tissue in the field and analysis of total nutrients in plants in the laboratory. Plant analysis is based on the relationship between nutrients in a plant and nutrient availability in a soil. Plant analysis is not a direct method of soil fertility evaluation, but it can serve as a valuable supplement to soil testing in the task of soil fertility evaluation. Plant analysis is useful in confirming nutrient deficiencies, toxicities and imbalance and identifying hidden hunger. Plant analysis generally provides more current plant-based information than soil testing, entails more effort in terms of sampling, sample handling and analysis and, perhaps, expensive.

In agricultural systems, water quality is usually determined to  assess its suitability for irrigation and/or its use for aquaculture. Analysis of irrigation water is carried out, to know their nutrient load, suitability for irrigation purposes in general and to salt sensitive crops in particular, and their significance as nutrient suppliers as in practical crop production (Tandon,1993). For aquaculture, on the other hand, maintenance of pond environment for survival and growth of aquatic lives, forms the major purpose of such exercises. While both the assessments are mostly governed by some common variables, a few additional attributes are also used for identifying the water quality for these two different purposes. The most important characteristics, that determine the quality of irrigation water are:

Earth provides enough to satisfy every man’s need but not every man’s greed. —Mahatma Gandhi The term ‘environment’ is derived from French word ‘environner’, which literary means ‘to surround’ or ‘to encircle’ i.e. everything either living (plants, animals, microbes) or nonliving (soil, water, air, temperature, humidity etc.) surrounding us makes our environment. The universe is full of uncountable number of stars, planet and satellites, which has specific type of environment but earth is the only known planet in the universe that contains life supporting environment. The earth environment is a collective term for the nature or ecosystems, that we use and benefit from on a local, national and global scale. The earth ecosystems provide number of benefits called ecosystem services, free of cost.

Spatial variability in soil parameters including nutrients has been attributed to the parent material, topography, landforms, cropping pattern, fertilization and manuring practices.. Blanket nutrient recommendations further widen the variability and enhance the risk of soil degradation in terms of soil organic carbon and nutrient mining, acidity, green house gas emission, water and environmental pollution. Unfavorable economics on account of blanket recommendation, adversely influence farmers to increase investments in new crop management technologies. This results in low farm productivity and poor soil health, that jeopardize food security and agricultural sustainability.

1. Why Plant Nutrient Disorders? Plant Nutrient Disorders result from nutrient imbalances in soils and plants. In-adequate use of one or more nutrients can result in nutrient imbalances. Presence or use of a nutrient in excess amount can hinder the absorption or uptake of another nutrient and thus,cause nutrient disorders. Lime induced iron chlorosis or use of excess Potassium can hinder the absorption of Ca2+/and, or Mg2+ by plants. Enhanced level of Mg can decrease the uptake of Zn. Excessive use of NPK fertilisers can result in micronutrient deficiencies. Soils are being regularly depleted of their native reserves, due to intensive cropping and non-application of essential nutrients (primary, secondary and micronutrients). Lack or restricted use of quality organic manures, such as compost, green manures, crop residues etc. and cultivation of HYVs in most crops have accentuated the problem.