eChapters

Tomato varieties produced 50% in plastic house cover more than what they produce in open air (Diez et al., 1985). Nevertheless this production increase is not, by itself the reason for the use of protected cultivation which requires higher expenses. The key factor is the cost increase of final product obtained during off-season, which created an interesting margin in spite of high production costs. The effect of cost of seed in total cost is negligible, which permitted the use of hybrid seed. The new hybrids have brought about production increases which can be calculated to be over 50% more than what the greenhouse varieties produced with the cost of hybrid seed giving an effect on total production costs of only 6-7%. So that under these circumstances, production increase associated with hybrids is certainly very advantageous, apart form other benefits to be derived from hybrids.

R aising of healthy vegetable seedlings is most important aspect in vegetable production, because, up to a large extent it determines the productivity and profitability. Nursery raising under open field conditions suffers by a number of biotic and abiotic factors like, continuous rains, too low and too high temperatures, disease and insect-pest etc. For the early establishment in the field and to reduce the cost of production, vegetable seedlings are being raised in plug trays under controlled conditions round the year. Under this system, each transplant grows in an individual cell to reduce the competition among transplants and maintain the uniformity. Plug transplants establish better in field because roots are not damaged in pulling, transplants often result in better stands, and their growth can be controlled more easily through fertility and water management. With the passage of time, a lot of advances have been made in this direction and a number machines have been developed like media sterilizer, media mixer, plug trays filling, seed sowing machine, growth chamber etc. by which the raising of seedlings under controlled environment becomes easier and labour intensive.

The growth is insulated to allow for heating or cooling according to specific germination needs of the seed. This technique reduces fluctuations in temperature and moisture that can occur in an open house. The growth chambers are usually an insulated room in which temperature and relative humidity can be maintained at a precise level. Air circulation is important to ensure uniform temperature and humidity throughout the chamber. Grafting in vegetables is a recent practice to control soil-borne diseases and nematodes, for both field and greenhouse grown crops. In addition, grafted vegetables can produce higher yields and have improved tolerance to environmental stresses, soil salinity and low soil temperatures which is only possible under protected conditions. Thus under present scenario, raising of seedlings under controlled environment offers opportunity to go for commercial nursery with different machines.

In India, risk-prone, high altitude area constitutes the easternmost trans-Himalayan part of Ladakh and Zanskar range (Jammu and Kashmir) and some parts of Lahoul Spiti (Himachal Pradesh). Truly described as cold desert with low population density, Ladakh constitutes the easternmost trans-Himalayan part of Jammu and Kashmir in India, comprising two districts, Leh and Kargil, bordering Pakistan and China (Fig. 1).

Greenhouse essentially functions based on solar energy to control environment for protecting cultivation from adverse condition. Computer simulation and mathematical modeling are important tools for determining the energy efficient design as well as predicting the overall system performance. The greenhouse climate may be used for crop drying, distillation, biogas plant heating, space conditioning, and aquaculture. Thus, any required configuration of greenhouse can be thermally modeled for predicting and optimizing the performance. The solar energy based greenhouse modeling are useful in evaluation of various applications like greenhouse heating, greenhouse cooling, greenhouse drying and aquaculture greenhouse. Greenhouse clubbed with ground air collector increase in plant and ambient temperature of 5–7°C during night in winter. Whereas, using evaporative cooling pad with greenhouse reduces the ambient temperature of 4–5°C during midday summer. A greenhouse can be very well used for large-scale crop drying, while not in use for cultivation. Some other applications such as covered crop drying and aquaculture are also discussed.

P rotected cultivation technology envisages immense promise, especially for high-value crops against various biotic and abiotic stresses. The climatic parameters stress conditions like unusually low and high temperature, humidity, solar radiation, wind velocity comes under abiotic stresses. The present climate change scenario dealing with various biotic and abiotic stress conditions poses serious threat to agricultural production throughout the world. It is estimated that due to one-degree rise in temperature during rabi season, wheat production declines by 4-5 million tonnes in India. Similarly due to prevailing low temperature and frost like conditions, especially in Northern India, several million tonnes of horticultural crops like tomato, brinjal etc. got wasted every year. Protected cultivation technology deals with following types of protected structures :

Growing population, rapid urbanization and changing climate have created a global challenge to meet the food and nutritional needs. In India, rapid urbanization is not only taking place in larger cities, but satellite towns are competing for food, water, transportation and above all adding to pollution of the environment. As warming of the climate gathers alarming pace, posing a danger to agriculture, greenhouse cultivation is the only answer to save crops of flowers and vegetables. The yield under polyhouse cultivation can be achieved to the level of 5-8 times as compared to open field cultivation.

PROTECTED STRUCTURES

Protected cultivation is unique and specialized form of agriculture. Protected or greenhouse cultivation of vegetables is one of the means for clean vegetable production in peri-urban areas. The protected cultivation facilitates year-round production of high- quality produce with minimum labour and irrigation water, and almost wards off pest problem. In peri-urban regions, where climate prevents or does not favour year-round production of crops in open field, vegetable production can be taken up in protected environment. Use of protected structure for cultivation of crops as a commercial venture is a recent phenomenon, especially in the tropical areas.

Greenhouse refers to a structure which provide relatively better environment for plant growth. The goal is to create congenial temperature and relative humidity in desired range. The greenhouse covered with polythene sheet, also called as polyhouse, has polythene sheet (UV stabilized 200 micron LDPE sheet) as covering over a relatively rigid frame (made of GI pipes, angle iron, boomboo or wooden) which entraps the solar energy to increase the temperature and provide light for plant propagation. A normal greenhouse has four basic components: 1) frame made from rigid material like GI pipes, wood or bamboo; 2) glazing material, which is transparent to provide enough light for plant propagation; 3) climate control system, which may be natural ventilation or forced ventilation using fans with or without cooling pads, shading nets, pigment painting, etc. and 4) plant growing medium (soil or artificial media like cocopeats) with needful arrangement for supplying inputs (water, fertilizers, pesticides, etc.). The design of greenhouse involves structural design of frame with enough climate control mechanism. It mainly depends on shape, size, material of frame, local climatic conditions, wind pressure, and desired height from crop production point of view. Fabrication of greenhouse should be such that it provides enough structural stability with wind pressure and other factors, perfect joints, anchoring of polythene, and minimum hindrances in crop production practices.

Protected structures such as cloches, low tunnels, greenhouses, livestock housing, aquaculture facilities and phytotrones provide varying degrees of climate control for agricultural production. While cloches and low tunnels provide only passive modification of the growing environment, all other protected structures have the possibility of active and precise growing environment control.

GREENHOUSE TECHNOLOGY

Greenhouse technology permits the management of both biotic and abiotic stresses related to plant growth to maximize the productivity and quality. Resultantly, profitability per unit area per unit time increases by two to three orders of magnitude as compared to open field cultivation. Introduction of greenhouse technology in India for commercial production is only about three decades old, whereas it is more than two centuries old in USA, UK, Holland, France, Italy, etc.

A greenhouse is a framed or inflated structure covered with a transparent or translucent material where plant environment could be, at least partially controlled and which is large enough to permit a person to enter and carry out cultural operations. A greenhouse is called a glasshouse, when covered with glass, and plastic house when plastic is the glazing material. Materials of construction and cropping activities are also used to identify greenhouses. In addition to the growing facility, a commercial greenhouse complex has a head house, an input storage and a sales area. All these components are so arranged that unwanted movements of man and material are obviated.The greenhouse complex should have adequate wind breaks on the upstream side of the wind direction to provide protection against heavy winds.

Protected cultivation of vegetable crops refers to creation of favourable environmental conditions around vegetable plants, offsetting or minimizing the detrimental effects of prevailing or expected to prevail abiotic and biotic factors. In open fields, vegetables face several abiotic and biotic stresses, resulting in lower or poor or no yield. This condition is altered by using different protected structures for cultivation and/or nursery production. Vegetables which are transplanted using seedlings should be produced by raising seedlings under protected conditions. Protected conditions ensure production of healthy seedlings. The use of healthy seedlings ensures better and higher production of vegetables both under protected conditions and open field conditions. Nursery grown in nursery trays can be transported long distances and can wait till field is ready or human resources is available for transplanting. Structures are ideal for production of plug plants/transplants in different sizes of portable trays.

Since ancient times, agriculture is an outdoor or open field production of crops. Open field production is climate and weather dependent. In fact, growth and development of crops under a particular set of climate parameters defines geographical location, productivity and production period of different crops. The magnitude of impact of climate and weather on agricultural productivity and quality of produce is appreciated by farmers and the scientific community, including horticulturists. Abiotic and biotic factors govern crop production potential and quality of products. Among the major constraints in production of horticultural crops are temperature (hot or cold), sunlight duration and quality, water deficiencies or excesses, atmospheric moisture (relative humidity), weeds, deficiency of nutrients, heavy winds, carbon dioxide and host of diseases and insect pests. There are ecological optima for obtaining production potential of each of the crops. Deviation from these conditions results in yield losses partially and sometimes totally. However, near optimal climatic conditions could be created by controlling the climate with the help of greenhouse using

The article is the Inaugural address delivered by Dr. R.S. Paroda at Indian Society for Protected Cultivation (ISPC-registered in March 2012), New Delhi on 21 March 2013 in a seminar ‘‘Advances on Protected Cultivation’’ at NASC, Complex, Pusa, New Delhi different protected structures/methods/devices and such cultivation under controlled environmental conditions is termed as as protected cultivation.

Introduction

Globally, the SOC pool of 1,550 Pg (1 Pg = 1015 g) to 1-m depth is about three times that of biotic and twice that of atmospheric pools (Post et al. 1982, Watson et al. 2000). In arid and semi-arid ecosystems, SOC contents show high degree of spatial variability due to patchiness of vegetation (Wiesmeier et al. 2009). The arid ecosystem might play a key role in mitigation of climate change effects through sequestering carbon in soils (United Nations 2011). Therefore, a suitable land use system having high C sequestration potential for arid ecosystem needs to be identified and promoted. However, the prevailing conditions of arid ecosystems normally does not support dense vegetation. Therefore, low carbon stock is expected in both above-ground vegetation and below-ground soil. Fruit trees are an integral part of arid farming system and played a significant role to improve the nutritional security and employment opportunity of farmers but also have potential role to increase carbon storage both in biomass and soil. To quickly assess the soil carbon restoration programmes, it is important to know how much soil carbon is stored in an agricultural farm through adoption of different land management practices. Therefore, reliable estimates of SOC pools are essential to establish the soil carbon sequestration programmes at different landscape scales.

Introduction

Soil organic carbon (SOC) content plays a key role in maintaining soil fertility in agricultural farm. At present, there has been great interest to reduce the atmospheric CO₂ level through a chain of increasing vegetation carbon pools first and then to store them as soil carbon pool. To quickly assess the soil carbon restoration programmes, it is important to know how much soil carbon is stored in an agricultural farm through adoption of different land management practices. Average SOC content is considered in most soil carbon pool calculations in spite of its large spatial variation in landscape, and thus leads to inaccurate estimate of SOC stock for an area. Therefore, reliable estimates of SOC pools and their spatial variability are essential to establish the soil carbon sequestration programmes at different landscape scales. Here, a case example of assessing the spatial variation at a typical agricultural farm is discussed. The experimental field was located at Badoda village of Jaisalmer district, Rajasthan covering an area of about 76.12 ha. The farm lies between 265^o2′30″-26°53′30″ N and 71°12′15″-71°13′15″ E (Fig. 24.1) and 20 km away from Jaisalmer city in eastward direction. Elevation of the farm ranged from 232 m to 248 m above mean sea level with an overall slope from south to north. Among total area of the farm, 85.38% area was under cultivation in four main blocks: block A, B, C, and D whereas rest area was under grassland.

Introduction

High degree of spatial variability in soil properties is observed at different scales. This variability is generally originated from the combined effect of physical, chemical or biological processes operating with different intensities at different scales (Goovaerts 1998). Knowledge of this spatial variationof soil properties is important in several land management applications e.g. variable rate application of nutrient and water in agricultural production system, land suitability classifications, modeling water balance components at landscape scales, precision farming etc. The concept of ‘management zone’ was also evolved in response to this large variability with the main purpose in efficient utilization of agricultural inputs with respect to spatial variation of soils and its properties (Franzluebbers et al. 1996, Atherton et al. 1999, Malhi et al. 2001). Therefore, an appropriate understanding of spatial variation of soil properties is essential. The most important way to gather knowledge in this aspect is to prepare soil maps through spatial interpolation of point-based measurements of soil properties. Here, a case study is discussed where soil water retention at two critical levels e.g. field capacity (FC) and permanent wilting point (PWP) was spatially characterized through geostatistical approaches. Because these two soil moisture contents guide farmers to apply right amount of irrigation water at right time. The study was carried out at the experimental farm of ICAR-Indian Agricultural Research Institute, New Delhi, India (28°37′-28°39′ N, 77°8′ 30″-77°10′30″ E, 217-241 m above mean sea level). A detailed discussion of the study is available in Santra et al. (2008)

Introduction

Microorganisms generally present in all the environments are the most abundant and diverse living organisms present on earth. Microorganisms have great impact on the biosphere due to their inbuilt ability to transform the key elements of life into forms usable by other organisms and plants. Because of heterogeneity in nature of soils from variations in physical, chemical and biological properties the various natural habitat are microbially most diverse environments on the earth maintaining the stability between complex microbial communities and their function (Daniel 2005). One gram of soil contains about 10 billion microorganisms of possibly thousands of different species but microbial diversity in general, and particularly in extreme environments, and its role in ecology is poorly understood (Rossello-Mora and Amann 2001).

Deserts present a unique environment with very little precipitation and large variations in day and night temperatures, making it inhospitable environment for living organisms. Still a number of microbial species do survive in those harsh environments. The populations of aerobic bacteria in deserts across the world are reported to vary from < 10 in Atacama desert to 1.6 × 10⁷ cfu g^–1 in soils of Nevada (Skujnis 1984), and India is not exception to that with the bacterial population in the range of 1.0 × 10³ to 8.35 × 10⁶ cfu g^–1 sediment or ml^–1 water in the samples collected from cold deserts of north western Himalayas (Yadav et al. 2015).

Introduction

The life support systems of a country and socioeconomic development of its people largely depend on soils. The soils are the most valuable natural resources for the society. It caters the basic needs of mankind by producing food, fibre and timber. It is therefore essential to know the distribution and extent of different soils and their qualities, potentialities and constraints for sustainable utilization of this valuable natural resource (Shyampura and Sehgal 1995). Information on distribution, potential and constraints of major forest soils are essential to design most appropriate soil management systems in order to increase productivity of forests as forests also offer excellent potential for poverty reduction and rural economic growth in India. However, unlike agriculture lands forest soils usually draw less attention and are ignored in spite of the fact that they nourish the lungs of the Earth. Soil quality is the most important factor in forest management decisions. Soils will determine productivity of a particular forest and management strategy. Knowing about forest soils can serve as a basis for forest management decisions, including land acquisition, species selection for planting, site preparation requirements, watershed development, fertilization prescriptions, stand density/ composition, and harvest timing, as well as decisions affecting land ownership and use.

Introduction

The natural resources of arid regions particularly soil and water are limited and is often in a delicate environmental balance. Desert encroachment due to lack of conservation planning, and the dangers of destroying or depleting beyond recovery these productive resources, are evident at present time and may be disastrous if development is based on short term expediency rather than long term stability.

The arid zone of India is spread over 38.7 million ha area, out of which 31.7 m ha in under hot arid region and 7 m ha under cold region. The hot arid region occupies major part of north-western India (28.57 m ha) and occurs in small pockets (3.13 m ha) in south India. The north-western arid region occurs between 22o30' and 32o05' N latitudes and from 68o05' to 75o45' E longitudes, covering western part of Rajasthan (19.6 m ha, 69%), north-western Gujarat (6.22 m ha, 21%) and 2.75 m ha (10%) in south-western part of Haryana and Punjab (Faroda et al. 1999). Rainfall distribution is highly uneven over space and time (CV>60%). The region receives low rainfall (<100 mm to 500 mm), has high evapotranspiration and high temperature regime (Rao and Singh 1998). Groundwater is deep and often brackish. The western-central area is devoid of drainage system and surface water resources are meager (Fig. 20.1). Due to low and erratic rainfall, replenishment of water resources is also very poor. The entire Rajasthan state is being categorized as the driest state and water scarce (having per capita water availability below 1000 m3 year-1) since 1991 in the country. Increasing pollution by industrial units, big and small, unregulated mining and even over-extraction of water from deep wells also add to the water quality problem in number of districts. Rapid urbanization and industrialization make such existing differences even more

Introduction

Soil is a dynamic natural body, characterized by high degree of spatial variability due to combined effect of physical, chemical or biological processes that operate with different intensities at different scales (Goovaerts 1998). Reports have shown that there is large variability in soil properties, crop yield, disease, weed etc., not only in large-sized fields (Godwin and Miller 2003,Vrindts et al. 2005), but also in small-sized fields (Bhattacharya et al. 2008). Therefore, knowledge of hydro-physical properties of soils is crucial for management practices for all kinds of agricultural practices for efficient utilization of input resources. Plant growth and development is highly related to soil hydro-physical properties, which not only depend on soil intrinsic textural and chemical characteristics (Hamza and Anderson 2005) but also on soil management.

Soil physical properties which change with the variation in soil structure include bulk density, total porosity, pore geometry (size distribution, shape, continuity and tortuosity), penetration resistance and aggregate stability, consequently affecting soil hydraulic properties such as water retention characteristics, plant available water capacity, infiltration capacity and saturated hydraulic conductivity. These soil properties are dependent on seasonal climatic conditions, management practices, crop development and biological activity (Reynolds et al. 2007). The hydro-physical properties of soils, i.e., water retention and water permeability in both saturated and unsaturated zones not only shape soil water balance but also decide the conditions for plant growth, development and yield. They also determine water availability for the plant root system and the transfer of water with chemical compounds dissolved in it into deeper layers.

Land resources units or major land resources units are the suitable segmentations of land, based on available natural resources, their potential use and management. Irrespective of terms used by different organizations or institutes, these units have spatial dimension and represent a composite unit for interstate, regional, and national level planning. A typical meaning of these land units can be related to terms like land system. Christian and Stewart (1953) of the Commonwealth Scientific and Industrial Research Organization (CSIRO), Australia devised the ‘Land system’ as the composite mapping-unit which has been defined as “an area or group of areas, throughout which there is a recurring pattern of topography, soils and vegetation”. This system is based on the premise that the land system is expressed on aerial photographs by a distinctive pattern and, as such, the land system can be directly mapped from aerial photographs (Christian and Stewart 1953, Mabbutt and McAlpine 1965). It is a fact that during those period, aerial photographs were more frequently used and studies related to land systems used technique of aerial photogrammetry. As per USDA (United States Developmental Agency), the typical segmentations are; (1) Land Resource Region (LRR), which is the highest level in the hierarchy (2) Major Land Resource Area (MLRA), the second highest level and generally representing broad landforms or a geologic region at a small scale and (3) the Land Resource Unit (LRU).

Concept and Definition

Desertification is a major problem in the drylands of India, affecting the way of life for its inhabitants. The problem is more severe in the arid lands in the northwestern part of the country. There have been a few numbers of definitions of the word “Desertification”. However for simplicity of its origin and meaning we would refer to two of the frequently used ones; (1) proposed in 1991 by UNEP: “Land degradation in arid, semi-arid and dry sub-humid areas resulting mainly from adverse human impact and (2) prepared for the Earth Summit at Rio, held in June 1992, for inclusion in Agenda 21, as “Land degradation in arid, semi-arid and dry sub-humid areas resulting from climatic variations and human activities. (Anonymous 1992).

Comparing two of these initial definitions, it would show that first one indicated desertification as a state of natural resources like soil and vegetation, mainly resulting from human activity while the second one included climate as a major cause. However, it reduced the emphasis of human activities as being the primary responsible factor and tried to link the possible impact of climate change on desertification. But the simplicity of the 1992 definition of desertification helped researchers to bring in sharp focus on the special environmental and socio-economic problems of the drylands.

So over the years, the key words that explains the term “desertification” has been changing or are being amended for specific purposes. This would at least mean that the problem of desertification is still debated world-wide, and its impact is not limited to some nations/regions as was presumed and discussed in first of UNCCD platforms. Therefore, as a precaution and combating this process, few catchy words like non-sustainable management, productivity, over-exploitation of natural resources, dryland livelihood, droughts are found to surround the word desertification. Earlier, some, people equated desertification with advancing boundaries of the existing desert and in India, examples of expansion / contraction of geographical boundary of Thar desert was a public debate among various researchers and planners. In the same time, some of the definitions tried to broaden its geographical scope so that greater populations suffering from adverse effects of land degradation would benefit out of various remedial measures.

Introduction

In India, hot arid ecosystem covering an area of 31.7 million ha lies at north western part of the country and 62% of this area falls in western Rajasthan covering 12 districts i.e. Jodhpur, Jaisalmer, Jhunjhunu, Sikar, Hanumangarh, Sri Ganganagar, Bikaner, Barmer, Pali and Sirohi. The major landforms in arid western Rajasthan are dune and inter-dune plains having sandy to sandy-loam textured soils. Temperature remains high for most part of the year reaching up to 42-45°C during prolonged summer months (April to July), whereas annual rainfall is very low and highly sporadic (100-400 mm) mainly occurs during August and September. Annual potential evapotranspiration ranges from 1500-2000 mm. Loss of fertile top soil from denuded soil surface through wind erosion is frequent during summer months. The region is subjected to frequent occurrence of droughts, once in every three years, which further intensifies the process of desertification (Samra et al. 2006). Shorter growing period, sandy soils, very low available water capacity, inadequate nitrogen and phosphorus availability are the major constraints. Soils are prone to severe wind erosion, terrain deformation and nutrient depletion. The region is mostly mono cropped and double cropping is being practiced extensively in canal and tubes well command area. Extensive fallowing in the past even in very good rainfall years because of uneven undulating topography and severe windstorm are the cause of concern. Ground water is deep and is usually brackish, declining at alarming rate due to excessive withdrawal for irrigation and other purposes. The region, however, sustains on perennial vegetation of Prosopis cineraria, Tecomella undulata, arid shrubs and grasses, which are rich resources of fodder for animal because cropping is affected by vagaries of monsoon. During last two to three decades, a 2 to 3-fold increase in irrigated areas with cultivation of both kharif and rabi crops has been recorded and most of these increments are resulted through conversions from rainfed areas, grazing lands and sand dunes into irrigated areas.