eChapters

Introduction

Phosphorus (P) is a major nutrient in crop production, but is also a major constraint due to its low bioavailability in soils. It is 11th most abundant element on earth’s crust and a  vital component of DNA, RNA, ATP and photosynthetic system and catalyses a number of biochemical reactions from the beginning of seedling growth through to the formation of grain and maturity. Many factors influence soil P availability like type of parent material from which the soil is derived, degree of weathering and climatic conditions.

Introduction
 
The major challenges in 21^st century are food security, environmental quality and soil health. Besides, shrinking land holdings and increasing cost of inputs in India merit adoption of scientific use of plant nutrient for higher crop productivity. The soil fertility and fertilizer use project initiated in 1953 following a study by Stewart in 1947 which was the first systematic attempt in India to relate the knowledge of the soils to the judicious use of chemical fertilizers. The soil testing programme was started in India during the year 1955-56 with the setting up of 16 soil testing laboratories under the Indo-US Operational Agreement for “Determination of Soil Fertility and Fertilizer Use”. In 1965, five of the existing laboratories were strengthened and nine new laboratories were established to serve the Intensive Agricultural District Programme (IADP) in selected districts.

With the introduction of high yielding varieties and use of high analysis fertilizer in intensified agriculture under irrigation condition resulted in green revolution in our country. But continuous use of chemical fertilizer in indiscriminate manner without assessing soil also had adverse effect on productivity and environment. Though use of high analysis fertilizer ensured the high production but also resulted in acceleration of mining of native sources of nutrient. This has led to appearance of hidden hunger of several other essential nutrients and sustainability of our agriculture has become venerable.

Water and nutrients are the most important, and readily manageable, variables for producing a profitable crop. Efficient management of water and essential plant nutrients is imperative for achieving sustainable agriculture and maintaining necessary increase in food production to feed the burgeoning population while minimizing economic losses and environmental impacts. Technology here can play a catalytic role in striking a common ground between these environmental and economic goals. Recent advances in sensor technologies indicate that efficient nutrient management in crop fields can be attained through the application of Precision Agriculture (PA)-based geo-spatial technologies such as global positioning system, geographical information system, remote sensing,

Introduction

Nitrogen (N) fertilization assured centre stage for enhancing food production in developing countries especially after the introduction of high yielding and fertilizer responsive crop varieties. Almost half of the human population relies on N fertilizer for food production (Ladha et al., 2005), and about 56 percent of the N fertilizer is used for producing rice, maize, and wheat (IFA, 2002). It has contributed an estimated 40% to the increase in per capita food production over the past 50 years (Smil, 2002). However, excess use of chemical N fertilizer may negatively affect surface water, as well as groundwater, and the atmosphere (through leaching and runoff) through volatilization of N (Galloway et al., 2008).

Plant mineral nutrition is a sub branch of plant physiology which addresses issues on uptake of elements that plant needs to absorb from air or water or soil to grow and to live. Besides function of nutrient elements in plants, it also includes deficiency symptoms and how to address deficiency symptoms in a plant. Plant mineral nutrition and mechanism of uptake has two major aspects:

Introduction

“Non-monetary inputs are defined as those cultural operations which help to achieve high yield at no extra cost and whose cost does not change with the level of output”.
 
After the advent of green revolution, nutrient management has received the significant attention by farmer as well as researchers; as a result of which and coupled with the requirement for high yielding varieties, consumption of plant nutrient (N, P and K) increased tremendously. Variability was observed in fertilizer consumption between the states. 

Introduction

The Indian agriculture is very complex and carrying out multi-functionalities of providing food, nutrition and ecological security besides employment and livelihood for over 700 million people. Indeed, India has made a marvelous achievement in attaining self-sufficiency in food grain production after the introduction of Green Revolution which eventually resulted in maintaining all-time high buffer stock in warehouses of our country. Such rosy picture in production trends turned to be bleak in the past few years.

Introduction

It is well-known that soil testing is agronomically sound, beneficial and environmentally responsive tool for monitoring the nutrient as well as pollutant status of soils, and also for making precise fertilizer recommendations for various crops and cropping sequences. Soil testing with associated plant and water analysis is the only tool known which helps to control soil fertility. Nutrient supplying power of soils, crop responses to added nutrients and fertilizer and amendment needs can safely be assessed through sound soil testing programme. Monitoring of soil fertility, against depletion and accumulation of certain elements in toxic proportions over time, is also possible through appropriate soil tests. This also helps to economize on cost of fertilizers and also in increasing fertilizer use efficiency.

Introduction

To meet the food needs of the burgeoning population, India will need to produce 300 million tonnes of food grains by 2020. At present more than 75% of the total food grains produced in the country are of rice and wheat. Use of nitrogenous fertilizers has contributed much to the remarkable increase in production of rice and wheat in India that has occurred during the past three decades. During the last half-decade or so while fertilizer N consumption is touching new heights, the production of both rice and wheat is showing a trend of plateauing.

The global economy has adversely been affected to a considerable extent due to weather related disasters which are not uncommon in the recent past due to global warming and climate change. It is true in the case of the Indian economy too. The year 2010 was the warmest year ever recorded, followed by 2009 in India. The year 2015 was the warmest year globally. Model simulations indicate that a marked increase in rainfall and temperature over India would be seen during the current century. The maximum expected increase in rainfall is likely to be 10–30% over the Central India. Temperatures are likely to increase between 2 and 3^oC by the end of 2100 A.D. Greater number of high surges and increased occurrence of cyclones in post monsoon period along with increased maximum wind speed are also expected along the East Coast of the Country. As a result, the occurrence of floods and droughts, cold and heat waves adversely affected the foodgrains production to a large extent across the Country in one or other region as seen in 2014, 2012, 2009, 2004, 2002 and 1987. It is true in the case of plantation crops also, which are predominantly grown in the Humid Tropics like Kerala (8°15` N and 12°50`N latitudes and between 74°50`E and 77°30`E longitudes). As seen in previous chapters, summer drought and heavy rains including waterlogging during monsoon period is a threat to plantation crops production in the Humid Tropics to a considerable extent. Waterlogging and floods due to excess rains could be minimised by providing surface and subsurface drainage facilities in plantation gardens which will improve the soil health and nutritional status, in turn yields can be increased in plantation crops.

Coffee is grown at higher elevation across the Western Ghats between 750 and 1200 m amsl. It requires a certain degree of shade for its better performance. The annual rainfall over the coffee growing tracts varies between 1400 and 2600mm, having uni/bi-model rainfall with prolonged dryspell from November to May. It is more so over North of the Western Ghats. The mean annual maximum temperature varies between 24 and 30⁰C while the minimum between 15 and 18⁰C. The difference between maximum and minimum temperatures (temperature range) varies between 5 and 16⁰C across the coffee tract. The ‘Monsooned Malabar Coffee’ is a specialty coffee produced from the erstwhile ‘Malabar Region’. It undergoes certain changes in physical and biochemical characters when the coffee beans are processed during the summer monsoon (June to September). It is processed at Mangalore, located in Coastal Karnataka. The processing location experiences heavy rainfall of more than 1000 mm in July, followed by 950 mm in June and 600 mm in August. Out of 3264 mm of annual rainfall, 2852 mm is received during the monsoon period. It accounts more than 80 per cent of annual rainfall. The maximum temperature during the monsooning varies between 28 and 30°C while night temperature revolves between 22 and 24°C. Being located in the tropics along the West Coast, the crop processing environment in terms of surface air temperature is relatively uniform and moderate with a characteristic feature of heavy clouds and continuous rainfall during the monsoon period.

The State of Kerala under the Humid Tropics is one of the wettest places in the Humid Tropics where annual rainfall is of the order of 3000 mm, ranging from less than 1000 mm to greater than 5000 mm. About 68 per cent of the rainfall is obtained during southwest monsoon while 16 per cent in post monsoon and the rest from summer (14 per cent) and winter rainfall (2 per cent). Bi-model rainfall pattern is noticed towards southern districts due to influence of both southwest and northeast monsoons while uni-model rainfall pattern towards northern districts of Kerala. Coconut productivity is better towards south despite dreaded disease of root-wilt when compared to that of northern districts due to less dryspells during summer. Floods during monsoon adversely affect paddy production in the State while prolonged droughts during summer in the absence of post monsoon rainfall adversely affect plantation crops’ production to a considerable extent. The wetlands in Kerala are rich sources of water during summer and act as sink during monsoon season. Such wetlands are fast declining in Kerala and converted as garden lands. Decreasing wetlands might be one of the reasons for frequent floods and droughts in Kerala in recent years. The forest cover of Kerala also declined from 70 per cent to 24 per cent over a period of one- hundred- and - fifty years due to deforestation and forest fires.

Tea (Camellia sinensis) is one of the most important beverage crops in the World and the second most commonly drank liquid on earth after water. It has numerous medicinal benefits mainly due to its antibacterial and antioxidant properties. The major tea growing regions of the world are South-East Asia (India and Sri Lanka), Eastern and South Africa consisting of Kenya, Malawi, Tanzania, Uganda and Mozambique. All these countries are producers of black tea. China and Japan are the major producers of green tea.

Black pepper (Piper nigrum L.), famous as “Black Gold” and also known the “King of Spices” is the most important agricultural commodities of commerce and trade in India. It is the most important, most popular and most widely used spice in the World. Of the total spices traded internationally, black pepper accounts for 34 per cent. South West India is the traditional home of this important spice, particularly the Malabar Coast. Black pepper is also grown in tropical zones such as the Asia Pacific Region, mainly India, Indonesia, Malaysia, Sri Lanka, Thailand, China, Vietnam and Cambodia. Outside the Asia Pacific region, the crop is distributed in Brazil, Mexico, Guatemala, etc., totaling about 26 countries. It is grown successfully between 20°N and 20°S latitude and from mean sea level to 1500 meters above sea level. World’s black pepper production varies in the range of 2.7 to 3.35 tonnes annually.

The natural habitat of rubber (Heavea brasiliensis) is rain forests of the Amazon basin, situated within 5° North and South at altitudes below 200m. The climate of this region is equatorial monsoon type characterized by mean monthly temperature by 25 to 28°C, well distributed rainfall and no marked dry weather. Though it is originated in the Amazon basin, it is now predominantly grown in the tropics where an equatorial monsoon type climate prevails. Regions between 8°N and 10°S which includes Indonesian archipelago, Malaysia, southern part of Sri Lanka and some other Islands, are better suited to rubber cultivation. The production of natural rubber in the country was 8.65 lakh MT in 2008–09, registering a 4.74 per cent growth compared to the previous year.

Small cardamom (Elettaria cardamomum Maton), popularly known as the “Queen of spices”, occupies an important position among the foreign exchange earning commodities. Cardamom is cultivated on a commercial scale in Sri Lanka, Guatemala, Tanzania and Papua New Guinea. Guatemala is the largest producer of cardamom in the World. In India, it is confined to the States of Kerala, Karnataka and Tamil Nadu, accounting for an area of 41588 ha, 25021 ha and 4561 ha, respectively (Spices Board, 2009). Among these States, Kerala accounts for the major portion of production (58.4 %), followed by Karnataka (35.2 %) and Tamil Nadu (6.4 %). In Kerala, Cardamom is mainly grown in the erstwhile Travancore area in the present Idukki district and it is known as the Cardamom Hill Reserve (CHR), which was specially reserved, denotified and removed from the control of forest development by the orders of the Travancore Government. By a Royal Proclamation in Medam 997(ME) 334 square miles (86,506 ha) area in Devikulam, Udumbanchola and Peermedu taluks of the present Idukki District was declared as CHR for the promotion of cardamom cultivation (Miniraj and Nybe, 2007). Cardamom is a native of the moist evergreen rain forests of the Western Ghats of South India and is grown extensively in the hilly regions at elevations of 700 to 1300 metres as an under crop in forest lands. Cardamom thrives well within certain thermal regimes. It is believed that diurnal symmetries in temperature trends, if any, have close links with the changes in cloudiness, humidity, atmospheric circulation pattern, winds and soil moisture (Kumar et al., 2002).

The global production of cocoa is around 36.49 lakh tonnes against the demand of 37.37 lakh tonnes. Ivory Coast leads in cocoa production in the world with a contribution of 38 per cent, followed by Ghana and Indonesia. Unlike in other crops, it appears that the production and demand of cocoa at the global level match each other to a large extent. However, the recent trends in the world production of cocoa beans indicated that there was a drop of nine per cent in 2006–07, declining from 3.8 million tonnes in 2005–06 to 3.4 million tonnes in 2006–07 (Table 9.1). It was attributed to unfavourable conditions in many cocoa producing areas. West Africa, the main cocoa producing region, was hit by a severe harmattan (dusty dry wind from November to March) and its inherent dry weather, which lasted from the end of 2006 to February 2007, had a strong negative impact on global cocoa production. In Asia and South America, El Nino- related weather conditions developed in September 2006 and continued until the beginning of 2007. It led to relatively low cocoa production in 2007–07. However, it was rebounced in 2007– 08 to some extent though it was low (36.49 lakh tonnes) when compared to that of 2005–06. The favourable weather which prevailed over most of the cocoa growing regions during 2002–03 and 2003–04 helped to achieve better production during the above years while dip in the global production in 2006–07 due to unfavourable weather. It reveals that the weather abnormalities like floods, droughts, cold and heat waves across the cocoa growing regions of the world adversely affect the Coca production and the cocoa industry is likely to suffer.

Cashew (Anacardium occidentale L.) is a very important horticultural crop which fetches considerable foreign exchange to India. The crop is a native of Brazil and was introduced in India by the Portuguese during 16^th Century. It is grown in India, Brazil, Vietnam, Tanzania, Mozambique, Indonesia, Sri Lanka and other tropical Asian and African countries. The crop is grown within the latitudinal belt of 27°N and 28°S of the equator experiencing a tropical temperature for its growth and development (Rao and Gopakumar, 1994). The trend in productivity has a phenomenal bearing to the distance from the equator. The world production of cashew is estimated to be around 20.8 lakh tonnes. The global productivity level of cashew is 690 kg/ha. Since 2000, the world raw cashewnut production registered an increase of 40 per cent. India’s share in the world raw cashewnut production accounts to about 25 per cent. In recent times, India is facing tight competition from Vietnam and Indonesia in international cashew trade. Since its introduction in the Country, cashew has well adapted to the Indian climatic conditions and is grown in the East and West Coasts of India. Now, India is the largest producer, processor, consumer and exporter of cashew in the world (Bhat, 2009 a). In India, cashew is grown mainly in Maharashtra, Goa, Karnataka and Kerala along the West Coast and Tamil Nadu, Andhra Pradesh, Orissa and West Bengal along the East Coast.

The Coconut palm, also known as the Cocos Nucifera L., is one of the most fascinating and beautiful palms in the world. Epigraphical, literary and sculptural evidence provide proof that coconut has served humanity for more than three millennia. The palm is looked upon with reverence and affection and is referred to by such eulogistic epithets as “Kalpavriksha”, tree of heaven, the tree of abundance, nature’s super market, king of palms and the tree of life. The coconut is believed to have originated in Southeast Asia (Indonesia, Malaysia, Philippines) or Micronesia (Harries, 1977; Purseglove, 1968 and 1972). Coconut has been cultivated in India since ages and plays an important role in social, economic and cultural activities of the people. The palm is amenable to both plantation and homestead management and it can be either a major crop or a minor one in a homestead garden of mixed crops. While responding favourably to scientific management, the palm also tolerates negligent farming to a certain extent. Thus, it can adapt to the divergent farming situations and management practices that are prevalent in different agro-climatic regions. The coconut palm is usually found near the sea on sandy beaches where it can tolerate salt spray and brackish soils. It is also grown under different soil types such as loamy, laterite, coastal sandy, alluvial, clayey and reclaimed soils of the marshy low lands. The ideal soil conditions for better growth and performance of the palm are proper drainage, good water-holding capacity, and presence of water table within three metres and absence of rock or any hard substratum within two meters of the surface. The coconut palm can also grow well inland, within altitudinal limit of 600 m to 1752 m in the Tropics. It requires an equatorial climate with high humidity. A year-round warm and humid climate favours the growth of coconut. The ideal mean annual temperature, which can be tolerated by coconut palm, is around 27ºC with 5–7ºC diurnal variation. The palm does not withstand prolonged spells of extreme weather/climate variations under rainfed conditions. A well-distributed rainfall of 1300–2300 mm per annum is preferred. It is known as a coastal tree since it is grown along the Coasts and Islands and does not tolerate high temperature range, that is the difference between the maximum and minimum temperatures.