Rain which is the main source of irrigation water has been testing the rainfed farmers in various parts of Tamil Nadu. In most places, farmers repeatedly express that they are not getting rain in the respective months and so their crops are affected. In some places they say that they have lost 'Adi' season itself, leading to vanishing of groundnut in their cropping system. They also repeatedly express that the total amount of rainfall have declined in the last two decades. They add that there is a variation in distribution of rainfall which affects the crop. Dry spell during the critical stages affects the crop yield significantly. Frequent crop failure is common in rainfed areas. In addition to the drought led disaster, excess rainfall damages the crops completely in some years. These disasters compel the farmers to switch over to alternate livelihoods.

More than the quantity, the distribution of the rainfall decides the crop yield under rainfed situation. Time of sowing is critical which is decided by the rainfall. Scientific analysis of the rainfall data is needed to take decision on the time of sowing. With the implementation of PURA (Providing Urban Amenities in Rural Areas) concept and emerging Knowledge Centers in Villages, it is possible to reshape the existing cropping pattern in tune with the available natural resources for making the agriculture viable and durable. The changes in the rainfall behaviour need to be studied and analysed. The farmers’ experience and knowledge on rainfall pattern need to be documented and triangulated with the scientific data. The result obtained from the study could be extrapolated to akin sites.

Nattrampalli block with Vannapatti soil series and bimodal rainfall, Thirumangalam taluk with vertisol and unimodal rainfall and Vedaraniam with sandy loamy soil and unimodal rainfall would be the desirable sites for exercising scientific study on the development of cropping pattern. Nattarampalli and Thirumangalam locations have been affected by severe drought continuously for about 4-5 years. During the last year those areas were affected by the flood.

Vedaraniam is a coastal taluk where deficit rainfall or excess rainfall affects the crop yield frequently. To give an example, in the year 2003, farmers faced crop loss owing to deficit rainfall. But during the year 2005, they faced complete crop loss due to heavy flood. In the year 2004, complete crop loss was recorded due to the entry of tsunami water in the agricultural fields. In addition to the crop loss, the agricultural lands have been affected by the salts deposited due to tsunami. Hence, the agricultural lands need to be reclaimed. We also need to find out some salt resistant crops specially to this area to ensure reasonable yield to the farming community.

The research aims at designing and testing efficient cropping pattern specially tailored for the selected rain-fed taluks employing scientific approaches and participatory research methods. The specific objectives of the research are:

• To evaluate the existing cropping pattern for it’s strengths and weaknesses with regard to the available resources.
• To identify the potential component crops of a resource based new cropping pattern.
• To develop a new cropping pattern that is socially and economically viable and environmentally adaptable.

• Village level farmers' workshop (two before and one after the study)
• Participatory Rural Appraisal
• Secondary data collection from different sources and analysis
• Collection of potential Evapo-transpiration (PET) data
• Analysis of rain fall data for length of growing period, Marcov Chain analysis to identify wet and dry spell, water balance study, Return period of annual rainfall, computing moisture availability Indices, coefficient of variation, extreme rainy events, initial and conditional probability of seasonal rainfall, onset and withdrawal of seasonal rainfall, sowing rain with in the season, weekly analysis of rainfall.
• Computation of efficient crops
• Analysis of collected data for moisture particulars
• Developing new cropping pattern
• Ex-ante analysis for all-purpose