eChapters

    1.    Salt affected soils;
    2.    Classification of salt affected soils; 
    3.    Formation of salt affected soils; 

    1.    Acid soil
    2.    Causes of soil acidity   
    3.    Problem of soil acidity 
    4.    Management or Amelioration of soil acidity 
        a.    Lime requirement (LR): 
        b.    Liming reaction in soils      
        c.    Benefits of liming on acidic soils 
    5.    Calcareous soil  
    6.    Formation, characteristics & management of calcareous soil 

Organic matter and its composition 
Decomposition  
Types microorganisms involved 
Enzymes involved in decomposition process?

N-Transformation and availability in soils     
    a.    N-Cycle 
    b.    N transformation in  soils 
Phosphorus transformation & availability in soils: 
    a.    P-Cycle 
    b.    P transformation in soils 
K-transformations& availability in soils: 
    a.    K-Cycle 
    b.    K-Transformations

The following graph is a visual representation of how plant growth and/or yield is affected by nutrient concentrations

Terminology

    ·    Nutrient: Nutrients are substances required by an organism for their normal     growth and reproduction. 
    ·    Plant Nutrient: The plant nutrient is a “food” which is composed of certain chemical elements often referred to as ‘plant nutrient’ or plant food elements considered very essential for growth and development of plants. 
    ·    Nutrition: The supply and absorption of chemical compounds needed for growth and metabolism of an organism.

Soil fertility -importance

From edaphological point of view soil is a medium for plant growth. It holds and nourishes the plants. Soil fertility refers to the ability of soil to supply plant nutrients. Soil fertility and fertilizers are very much closely related terms; and cannot be neglected one from the other in their function. Soil fertility acts as a ‘SINK’ where in plants can draw nutrients for maximum productivity, where as fertilizer, acts as a ‘SOURCE’ wherein we can apply continuously different nutrients. The importance of soil fertility and nutrient management is being increasingly recognized in all countries recently to meet the demand for food and other agricultural raw materials. Intensive use of fertilizer, intensive cropping and high yielding seeds have no doubt increased the food production and reduced the food shortage but it has also ushered in innumerable problems of soil fertility, soil and water pollution. On the other hand, fast depletion of nutrients due to over exploitation, a wide spread deficiency of N, P, K and S coupled with micronutrients deficiencies specially Zn, B and Mo is taking place. Further deforestation, shifting cultivation, burning of crop residues, trees, bushes, grasses and cow dung, soil erosion, nutrient losses and imbalanced nutrient application, leaching losses etc., have aggravated the depletion of soil fertility status. The productivity of Indian agriculture solely depends on scientific management of soil fertility along with judicious and efficient use of fertilizers integrated with organic sources.

Participation means different things to different people. They way participant is defined largely depends upon the context and back ground in which participation is applied. While the Economic Commission for Latin America (1973) considers contribution by the people to public programmes to the complete exclusion of any involvement in the decision making process as participation. Cohem and Uphoff (1977) maintain that participation tools includes the peoples involvement in the entire decision making process. Like Cohem & Uphoff, FAO (1982) emphasizes participation in all the decision making processes but by the people’s organization and through self organized action. Paul (1987) introduces the concept of enhancement of well-being in terms of values cherished by the communities as being the ultimate objective of participation.

Agriculture is world’s single largest employer and probably the most weather dependent of all human activities.  Climate and its variability have been and continue to be, the principal source of fluctuations in global food production. Throughout history, extreames of heat and cold, droughts and floods, and various form of violent weather have wretched havoc on the global agricultural production. With the unprecedented increase in population over past few decades, clearly the mankind faces undertaking task to ensure food and nutritional security for all, considering reduced per capita land, reduced availability of water, depleting biodiversity and need to preserve ecology and environment. In India, of the total geographical area of 328 m ha, about 175 m ha (53 % of total) are categorized as degraded land, of which 150 m ha are subjected to serious water and wind erosion (Singh et al. 1981). Crops are sown in about 180 m ha annually. Since it seems very much impossible to bring more area under cultivation we need to achieve greater efficiency in the natural resources use while conserving the environment by placing greater emphasis on understanding and exploiting climatic resources for the benefits of agriculture.

The Gujarat state is located on the north-west of India between 20^o6' N and 24^o42' N latitude and 60^o24' E to 74^o24' longitude. The climate of Gujarat is semi-arid tropical . the summers are very hot, the winter season is uncertain and irregular. The Arabian sea and Gulf of cambay have a moderating effect on the climate of the coastal areas of the state.

The state has a coastline of 1600 km (27% of the country) out of which Saurashtra and Kutch has about 1125 km long coastal line. The total coastal cropped area of the state is 8.75 lakh ha (9.11% of total cultivated area) spread over three agro-climatic regions of the state, out of which 91% comes under arid and semiarid climate type (Table 1). The important crops of the region are groundnut, bajara, sorghum, cotton, and wheat. The ground water availability is also scare. In the state recently the soil degradation through salinity has caught hold over 1.2 m ha of land, of which, about 0.3 m ha occurs in the coastal area. About 1125 km long coastal line is in Saurashtra and Kutch which comprises about 0.1079 m ha of saline land which needs to be treated for salinity reduction.
 

Importance

Drought is a climatic anomaly characterized by deficient supply of moisture, which may result from sub-normal, untimely and unevenly distributed rainfall. Among the various hazards of nature, drought is one of the major disasters because it brings innumerable miseries to the mankind. Almost every year some part or the other of the country suffers from such calamities. Drought is a recurring phenomena and its occurrence cannot be avoided. However, its impact can be minimized through application of science and technology by developing drought management plans.

For better yield irrigation water must be free from soluble salts and from concentration of specific chemical substances that may hazard to soil with respect to salinity, sodicity, alkalinity and toxicity. Water analytical data which helpful to predict the magnitude of the effect of irrigation water on soil and plant growth under specific environmental circumstances so irrigation water must be analyzed for EC, pH, Na+, Ca⁺⁺, Mg⁺⁺, Cl^-, CO₃–, HCO₃-  and SO₄.^– 

Agricultural land drainage is adopted for removal of excess surface and subsurface water, either from irrigation or rainfall in order to improve the profitability of land use.  Drainage also plays a role in removal of salts from the root zone. Therefore, land drainage is closely linked to irrigation in arid and semi arid regions. India has a long history of practicing irrigation and drainage in its semi arid irrigated regions. During the ancient times in the Indus Valley dams and drainage system were built for cultivation of different crops. The earlier experience of drainage was more concerned with surface drainage because from time immemorial India has been experiencing floods of varying magnitudes.

India is an agricultural country. The geographical area of India is about 328 mha out of which 147 mha of land under cultivation and 84-mha land is under irrigation. The population is increasing at an alarming rate that requires producing more food for the growing population. This problem can be solved either by increasing the land under irrigation or using different soil water conservation techniques. It is well known fact that during rainfall a considerable amount of water goes to sea due to high rate of runoff. It is highly needed to trap as much as water falling in the form of rainfall and recharge the groundwater so that it is made available for irrigation purposes.

Mulching

The technique of covering the soil with plastic films or natural crop left over (residues) for soil and water conservations is called mulching.

This technique was practiced by farmers using dry leaves straw, trash, stones etc to conserve water. Presently plastic film have come into use for the purpose of mulching due to inherent advantages.

Introduction

Salinity in India is a major issue affecting the sustainability of irrigated as well as non-irrigated areas particularly in the states of Rajasthan, Gujarat, Haryana, Uttar Pradesh, West Bengal and Orissa. Salt affected soils are unproductive unless excess salts are reduced or removed. These soils occur most extensively in arid and semi-arid climates, but these soils are also found in coastal sea areas where soils are unundated by ocean or sea water. Soils are said to be saline if they contain an excess of soluble salts and sodic or alkali if they contain an excess of sodium salts. Again soils are said to be saline-sodic or saline-alkali if they contain appreciable amounts of both soluble salts and sodium. The impact of salinity manifests itself in several ways. As the salinity increases, not only does the productivity decline but sensitive crops also go out of cultivation and are replaced by salt-tolerant, low value crops and other plant species.

Soil Erosion As a Process
 
Soil erosion is a three stage process, namely (1) detachment, (2) transport, and (3) deposition of soil. Different energy source agents determine different types of erosion. There are four principal sources of energy: physical, such as wind and water, gravity, chemical reactions and anthropogenic, such as tillage. Soil erosion begins with detachment, which is caused by break down of aggregates by raindrop impact, sheering or drag force of water and wind. Detached particles are transported by flowing water (over-land flow and inter-flow) and wind, and deposited when the velocity of water or wind decreases by the effect of slope or ground cover. Processes like dispersion, compaction and crusting, accelerate the natural rate of soil erosion. These processes decrease structural stability, reduce soil strength, exacerbate erodibility and accentuate susceptibility to transport by overland flow, interflow, wind or gravity. These processes are accentuated by soil disturbance (by tillage, vehicular traffic), lack of ground cover (bare fallow, residue removal or burning) and harsh climate (high rainfall intensity and wind velocity).

Aquaculture is the cultivation of fish, molluscs, crustaceans (shell fish) and aquatic plants in controlled conditions, provides an increasingly significant proportion of food production globally. The sector has represented the greatest growth of all food production systems in the last two decades and an estimated 10% yearly increase in output is likely to bring productivity to a predicted 47 million tonnes in the year 2010 (Pedini and Shehadeh, 1997). Significantly, the greatest contribution to total production and the greatest rate of uptake of aquaculture activity is in the developing world. More than 82% of the total global yield in 1999 was produced by developing countries (GESAMP, 2000) and growth rates between 1984 and 1995 were six times higher than that from developed countries (Rana, 1997; Tacon, 1996).

Groundwater is a precious renewable resource which gets replenishment from the precipitation. Total water resources of the world are estimated at 1.37 x 10⁸ million ha-m. Of these, about 97.2% is salt water, mainly in oceans, and only 2.8% is available as fresh water. And, out of this 2.8%, about 2.2% is available as surface water (2.1% is fresh water in glaciers and icecaps, 0.1% is available in lakes and reservoirs, 0.0001% in streams) and 0.6% is available as groundwater. Only 50% of groundwater resource is economically extracted with available technology. Presently, 1.3 x 10⁴ million ha-m fresh water in reservoirs and 41.1x10⁴ million ha-m groundwater is theoretically available to provide usable water for drinking, domestic use, irrigation, etc., to mankind. Groundwater is the largest source of fresh water excluding the polar icecaps and glaciers. The amount of groundwater within 800 m from the ground surface is over 30 times the amount in all fresh water lakes and reservoirs, and about 3000 times the amount in stream channels, at any one time.

Experiment

An experiment is a planned inquiry to obtain new facts or confirm or deny the result of previous experiment. Such inquiry can aid in an administrative decision, such as recommending a variety, a feed, a cultural practices, a fertilizer, a pesticide or a fungicide etc.

Type of Experiments

    1.     Preliminary experiments : Here investigator tries out large number of treatments in order to obtain leads for future work. Here replications are not taken for such treatments tried e.g. number of pesticides for control of diseases - take single observation for each treatment and take decision that some of them worth trying for use.