Environmental Concerns

 


Indian agriculture faces a serious challenge to ensure food security for every individual in the country. Current food grain production is estimated to cross over 200 million tonnes, but India will have to increase this to 250 million tonnes by the end of 2025 to meet the requirements of an ever-increasing population.

How to Ensure Food for Each
and Every Indian
Dr. B. N. Vyas


The application of neem-coated fertilizers has
proved beneficial for the growth of sugarcane.

he food grain production in the country, which was about 55 million tonnes in the early 1950s, increased to more than 200 million tonnes during 2003-04. This significant achievement of enhanced food grain production in independent India is mainly attributed to the availability of appropriate germ plasm, expansion of irrigation sources, increase in plant nutrient consumption and use of plant protection chemicals. It is believed that the Green Revolution was triggered by the availability of “miracle” seeds. In addition, it has been recognised that the realisation of the genetic potential of high yielding varieties is linked with the adoption of optimum land and crop husbandry practices. The gradual increase in the usage of major agri-inputs during the last three decades is shown in Table 1. Each of the basic crop production inputs, if used in isolation, is far less effective and it is only through a need-based and optimal mix of these inputs that agricultural production can be sustained.

There are 16 elements, called essential elements or plant nutrient elements, which are vital to the life cycle of plants. These essential elements are carbon, hydrogen, oxygen, nitrogen, phosphorus, potassium, calcium, magnesium, sulphur, zinc, iron, copper, manganese, molybdenum, boron and chlorine. With each harvest of a crop, a quantity of each nutrient is depleted. Replenishment of nutrients through exterior means is absolutely essential to sustain self-sufficiency in crop production. The beginning of the Green Revolution in the mid-1960s initiated a spurt in the use of chemical fertilizers, which is evident from the data given in Table 1.

Environmental Hazards
It is interesting to note that 40 to 70 per cent of applied nitrogen is not utilised by crops. In this context, besides the question of optimal use of fertilizer nitrogen by crops, there are the larger issues of environmental pollution relating to this phenomenon. While leaching losses of nitrates result in pollution of groundwater, the emission of nitrous oxide, especially from rice fields, leads to degradation of the ozone layer and contributes to global warming with serious implications on climatic change. On a global basis, a loss of merely 20 per cent of fertilizer nitrogen (total global nitrogen use is about 47 million tonnes) is equivalent to 9.4 million tonnes of nitrogen (nearly equal to the total nitrogen consumption in India), which amounts to U.S. $6.16 billion.

A survey of the literature of the past 25 years reveals that a large number of studies have been undertaken with regard to regulating the nitrogen transformation in the soil to ensure a continuous supply of nitrogen to match the requirements of crops at different stages of growth. The significance of neem and neem cake in increasing fertilizer nitrogen efficiency has been studied extensively. Data available from a large number of experiments on several crops, including rice in which losses of nitrogen are reported to be very high, reveal that increases in rice yield due to neem cake coating/blending of prilled area ranged from 0.9 to 54.2 per cent. The average increase in the yield of wheat, potato, sugar cane, cotton and finger millet was 6.9, 10.5, 15.5, 10.3 and 5.3 per cent, respectively. Data on other crops, namely jute, Japanese mint, maize and tea have also shown an increase in yield due to use of neem cake along with urea. " The first commercial neem-based urea-coating agent in the market was developed and introduced by M/s. Godrej Agrovet Ltd. under the brand name Nimin ". Nimin is self-adhesive and no external adhesives like coal tar, etc. are required. The farmer can pre-mix Nimin with urea before application to fields.

Besides neem-based products such as Nimin and neem cake, which have unequivocally demonstrated their ability to improve the crop use efficiency of fertilizer nitrogen, the use of Karanj (Pongamia glabra), Mahua (Bassia latifolia) and Ratanjyot (Jatropha curcas) cakes has also been reported to result in the enhancement of the nitrogen utilisation efficiency of crops. There are also reports on the nitrification inhibition properties of alcohol/acetone extracts of neem, Karanj and Mahua cakes as well as oils. Oil seeds, when used along with urea, can save substantially large quantities of fertilizer nitrogen vis-à-vis uncoated urea, and significantly reduce the detrimental effects of excessive nitrogen on the environment.

Phosphorus is another key element among the essential plant nutrients. Its use efficiency by crops is as low as 15 to 20 per cent. Hence, its effective management becomes all the more important. In this context, an interesting development is the coating of phosphatic fertilizers with a by-product of the pine oil industry, namely rosin, which can be highly effective in improving the phosphate use efficiency of crops. A significant reduction in phosphate fixation (immobilisation) in soils due to a coating of rosin on certain phosphates has been reported.

Organic Farming
Of late there is considerable interest in organic farming as the most holistic approach to crop production. In India, the area under organic farming is estimated to be only 0.03 per cent of the total cultivated area. Even in Europe and other developed countries, despite serious efforts and incentives, the area under organic farming is less than 5 per cent. There is no denying the fact that the regular use of organic sources has a remarkable effect in improving the physico-chemical properties of soil and ultimately soil health. However, these products serve only as a supplement rather than a substitute for fertilizers.

It is not only important to produce, but also to protect crops from pest damage. Annual crop losses in the country due to various pests, viz. insects, fungi, weeds, bacteria, rodents, nematodes, etc. are estimated to be nearly 30 per cent, amounting to Rs. 30,000 crores. Of these losses, weeds account for nearly 33 per cent, plant diseases for 26 per cent, insects and rodents for 26 per cent, while birds and nematodes etc. account for the remaining 15 per cent. Although crop losses due to insects and rodents are only about 26 per cent of the total, the share of insecticides among crop protection chemicals used in the country is over 70 per cent. The high level of consumption of insecticides in India is largely due to the fact that the warm and humid climate is conducive not only for the growth of lush green vegetation, but also for rapid multiplication of insects causing serious damage to crops as well as stored grains.

Role of Pesticides
Synthetic chemical pesticides have played an important role in reducing crop losses caused by pests and are likely to continue to be used in significant quantities in the foreseeable future. Currently India produces nearly 80,000 tonnes of technical grade pesticides.However, over a period of time, " Continuous and excessive use of chemical pesticides has resulted in serious ill-effects such as development of insect resistance, insecticide-induced resurgence of pests and toxicity to non-target organisms such as the natural enemies of insects, and human beings" .

There is an urgent need to evolve an alternative and coherent pest management programme, which is effective and environment friendly. In this context, use of bio-pesticides, namely neem, Bacillus thuringensis and Nuclear Polyhedrosis virus have gained significant importance in recent times. The use of botanical products is an extremely important approach for pest control in view of the fact that such formulations are based on multiple constituents, which greatly reduce the chances of development of resistance among pest species. Moreover, the use of plant-based products is dependent on constituents generally not required for traditional use such as soap-making or other uses based on oleo chemicals and hence, the availability of oils for non-agricultural usage is not likely to be adversely affected.


The use of Nimin-coated urea in paddy fields on the left has resulted in
 significantly improved yields, despite the lower nitrogen content.

The impact of synthetic chemical pesticides on insect pests is immediate and deadly. On the other hand, the effect of botanicals and neem compounds is indirect and hence these compounds exhibit a somewhat delayed response in insect pests as compared to chemical pesticides. However, there is an added benefit with neem preparations in that these are effective, in one way or another,at each stage of the life cycle of the insect, i.e. egg, larval, pupal, adult or egg, nymph, adult. A large body of data is now available on the effects of neem constituents on the biology of insect pests, including:

1) Settling behaviour or repellence
2) Feeding behaviour
3) Oviposition deterrence
4) Metamorphosis disruption or insect growth regulation
5) Reduced fecundity and egg sterility
6) Reduced fitness and vigour

It is evident that due to the multiplicity of their composition and effects on almost all stages of growth of insects, botanical formulations in general and neem products in particular offer excellent potential for the control of crop pests without any associated ill-effects.

In view of the above findings, during the past four to five years there has been a spurt in the development and marketing of neem-based pesticides in India. These products are derived either from neem oil or from the extracts of neem seeds and are recommended for the control of a variety of crop pests.


Table 1: Progress in Use of Agricultural Inputs

Inputs

1950–51

1970–71

1990–91

1994–95


1999-2000

 

2001–02

Certified Seeds (lakh quintals)

 

 

57.1

65.86

80.1

109.76

Fertilizer Nutrients(N + P2O5 million tonnes)

0.069

2.17

12.54

13.56

18.79

17.35

Pesticides Technical (thousand tonnes)



2.35
 

24.32

75.00

61.36

71.23

81.32

Source: Ministry of Agriculture

Damage Control
A significant amount of crops are lost every year due to damage by diseases and nematodes. In order to control such damage, chemicals called fungicides and nematicides are used in agricultural practice. Even though the scientific investigations on neem derivatives against insect pests began almost 50 years back, concerted efforts regarding their utilisation against plant pathogens and parasites such as nematodes, bacteria, fungi and virus started only during the mid 1960s.

The use of plant growth promoting chemicals (PGRs) is being increasingly recognised as a vital means of enhancing crop productivity in agricultural practice. During the past 25 to 30 years, a large number of endogenous plant hormones as well as other growth promoting chemicals such as triacontanol, seaweed extracts, protein hydrolysates, brassinolides etc. have been used in several crops for enhancing their productivity. Due to the unique actions of PGRs, their extremely low rates of applications and effects on enhancement of crop yields, with negligible adverse environmental impacts, plant hormones like brassinolides and triacontanol offer excellent opportunities in augmenting agricultural production. In this context, M/s. Godrej Agrovet Ltd. has been the global pioneer in developing PGRs based on brassinolides, which increase the yield and quality of several crops.
The biggest challenge for agricultural scientists lies in ensuring food security for the significantly large Indian population. Indian agriculture has made tremendous progress through the Green Revolution by raising its food grain production from 55 million tonnes in 1951 to over 200 million tonnes at present. However, it has to be borne in mind that this increase in production was brought about over 45 years, whereas the task of increasing our production from 195 million tonnes to 225 million tones has to be completed during the next five to seven years if every single individual in the country has to be provided with two square meals a day. This is possible only through massive application of scientific methods in farming practices, which would involve integration of several approaches namely, nutrient utilisation, enhancement of physiological efficiency of crop plants and pest management. In all these areas the development of environment-friendly products and their use in a cost-effective manner will continue to play an increasingly important role.

The writer is General Manager, Research & Technical Development, Godrej Agrovet Limited.
 

 

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