In this article we will discuss about the various crop growing seasons in India, with the help of suitable diagrams.
Each crop has its own sowing and harvesting seasons and it is important to have a knowledge of this which may help to decide the total water demand in a field having mixed crops.
In India, the northern and north eastern regions have two distinct cropping seasons. The first coinciding mostly with the South western monsoon is called kharif, which spans mostly from July to October. The other, called rabi, spans generally over October to March. The summer season crops are planted sometime between April and June. In southern part of India, there is no such distinct season, but each region has its own classification of seasons.
Generally, the kharif is characterized by a gradual fall in temperature, more numerous cloudy days, low intensity, high relative humidity and cyclonic weather. During Rabi, there is a gradual rise in temperature, bright sunshine, near absence of cloud days, and a lower relative humidity.
The following table indicates some the regional cropping calendars in India:
Variations in India’s Irrigation Demands:
It may be appreciated that in India there is a large variation of rainfall, which is the primary source of irrigation in most parts of the country. In fact, the crops grown in various regions have been adapted according to the local rainfall availability. Water resources engineers are therefore concerned with arranging supplementary water to support the crops for seasonal variations of rainfall in order to ensure an assured crop harvest.
Further, due to variation in the type of soil over different regions of the country, the types of crop grown also varies – thus dictating the water requirement at different regions during different times. Hence, the country has been broadly classified into eight agro climatic zones, a list of which is given.
Cropping Patterns:
Planning of an irrigation project requires estimation of water demand of a cultivated area. Naturally, this would depend upon the type of crop grown. Since irrigation water may have to be supplied to one field growing a combination of crops or to many fields growing different crops, it is important to understand certain cropping practices which would be helpful in estimating the irrigation demand.
Some of the prevalent practices are as follows:
i. Crops grown solely or mixed- Mixed cropping.
ii. Crops grown in a definite sequence- Rotational cropping.
iii. Land occupied by one crop during one season- Mono cropping.
iv. Land occupied by two crops- double cropping.
v. Land sowed with more than one crop in a year- multiple cropping.
Irrigation Water Need:
For raising a field crop effectively, it is essential to supply water through artificial irrigation supplementing the rain falling over the plot of land and raising the soil moisture.
Irrigation requirement for a typical crop and an assumed rainfall pattern may be illustrated as in Fig. 2.44.
Hence, it may be seen that irrigation water requirement is rather a dynamic one. Also, the crop water requirement is shown with slight variation, it actually shows more variation, depending on the type of crop and the prevalent climate. Though farmers may be tempted to allow more water to the plants through supplemental irrigation, it must be remembered that there is an optimum water requirement schedule of each crop depending upon its stage of growth. It has been proved that at times application of more water may cause reduction in yield.