SESSION—IV - AGRO-TECHNIQUES INCLUDING PLANT NUTRITION

Dr. K. L. Chadha presented the Keynote Address on ‘Present Status of Knowledge on Agro-techniques including Nutrition in the World’ and gave a general assessment of the knowledge on nutrition, irrigation, weed control, high density planting and pruning.

It became evident from the keynote address that fertilizer recommendations all over the world have been very empirical with regard to mango and there is wide variation in the doses of fertilizers recommended. There is, therefore, an urgent need for formulating a package of fertilizer management practices indicating the quantity, time and method of application. Even though there are some long-term fertilizer trials presently in progress in India under the All India Coordinated Project, more such trials need to be started under different soil and agro-climatic conditions. Changes in soil characteristics may be monitored periodically in such trials.

Information available on the root activity is meagre. Information on the distribution of root activity in different cultivars is very essential for evolving suitable fertilizer placement and irrigation practices, and for deciding plant densities. Studies on these aspects using isotopes, wherever facilities are available, may be initiated.

Although some work has been carried out to standardize leaf sampling techniques and to fix leaf nutrient guides through nutritional surveys of orchards, there have been differences in the recommended time of sampling and the critical nutrient levels. While the available information can be made use of, there is need to carry out more such studies to standardize the time of sampling and leaf nutrient guides as applicable under different agro-climatic conditions and varietal situations. These would be useful in monitoring the nutrient status of orchards and to make more precise fertilizer recommendations.

There is very little information on the irrigation requirement which is an important aspect. There is considerable area under mango which is presently irrigated and there is scope for extending mango cultivation in marginal unirrigated areas. Work on this aspect needs to be carried out urgently. Further, comparative efficiencies of different methods of irrigation, such as flood, drip and sprinkler methods have to be studied. Drip irrigation is already being used in other fruit crops not only for irrigation but also for applying fertilizer nutrients.

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