Influence of System of Rice Intensification on Yield, Water Use and Economics Through Farmers’ Participatory Approach

Eight hundred and thirty two on-farm demonstrations on System of Rice Intensification (SRI) were carried out in six hundred hectares of farmers fields in Sivagangai and Madurai districts of Tamil Nadu from 2007-08 to 2010-11 under Tamil Nadu-Irrigated Agriculture Modernization and Water Bodies Restoration and Management (TN – IAMWARM) Project. Two methods of rice cultivation viz., SRI and Conventional were compared. The results of large scale on - farm demonstrations revealed that adoption of SRI favorably influenced all the yield attributes of rice viz. number of tillers m -2 and numbers of grains panicle -1 . Superiority of SRI in terms of grain yield was also evident due to 24.0 per cent yield increment than conventional method of rice cultivation. Higher grain yield coupled with substantial water saving to the tune of 24.3 per cent resulted in higher Water Use Efficiency of rice under SRI method. Higher gross income, net income and benefit cost ratio were also associated with SRI than - conventional method of rice cultivation. The cost of cultivation was comparatively lesser in SRI which resulted in an additional net profit of Rs.13,340 ha -1 as compared to conventional method of rice cultivation.

Rice is the most water consuming food crop of India and Tamil Nadu. In Tamil Nadu rice crop alone consumes about 80 per cent of the total water available in the state. The present water status demands for the scientific management of available water efficiently to achieve the twin objectives of higher productivity and better water use efficiency. At present, non-availability of labour, escalating input cost coupled with water shortage leads to poor economic benefits in rice cultivation. System of Rice Intensification (SRI) is a modern and alternative method of rice cultivation for reduced usage of water and other inputs. The concept of SRI includes transplanting young seedlings, carefully, singly and widely spaced with soil kept well aerated. Large scale demonstrations of modern technologies like SRI in farmers field through farmers participatory approach will have great potential to improve the rice productivity and thus increase the standard of living of farming community. The Manimuthar sub basin is one of the sub basins in Tamil Nadu with a drainage area of 16751 ha. This basin comprises of four minorbasins viz., Manimuthar, Virisuliyar, Thirumanimuthar and Palar and it spreads over six taluks in three districts of the state namely Madurai, Sivagangai and Ramanathapuram. The major focus of this study in the basin is to promote water saving * 1 Corresponding author email: veeraagri@yahoo.co.in technologies, enhance crop and water productivity and increase the cropped area by diversification. Therefore an attempt was made to study the performance of SRI in comparison with the conventional method of rice cultivation in the Manimuthar sub basin area.

Materials and Methods
Eight hundred and thirty two on -farm demonstrations on SRI were carried out in six hundred hectares of farmers fields in forty six villages in Sivagangai and Madurai districts of Tamil Nadu from 2007-08 to 2010-11 under Tamil Nadu-Irrigated Agriculture Modernization and Water Bodies Restoration and Management (TN -IAMWARM) Project. The details of field demonstrations in the study area are furnished in Table 1. The available soil fertility status of the study area was low in nitrogen, high in phosphorus and potash and mainly sandy clay loam in nature. Two methods of rice cultivation viz., SRI and Conventional planting were compared by using the varieties ADT 36, ADT 39, ADT 45, ASD 16 and BPT 5204. In SRI, the concepts viz., lesser seed rate of 7.5 kg ha -1 raised in 100 m -2 mat nursery, square transplanting of 14 days old single seedlings at 25 x 25 cm spacing were followed. Irrigation water was applied at 2.5 cm depth after hair line crack formation upto panicle initiation and thereafter one day after disappearance of 5.0 cm ponded water and weeding using rotary or cono weeder at 10, 20, 30 and 40 days after transplanting (DAT) was practiced under SRI. In conventional method of rice cultivation, a seed rate of 30-60 kg ha -1 in 800 m -2 nursery area, transplanting 3-6 seedlings at 21-30 days age in a spacing of 15 x 10 to 20 x 10 cm, irrigation to 5 cm depth one day after disappearance of ponded water and manual weeding twice at 15 and 30 DAT were practiced. The total water use was calculated by adding irrigation water applied and effective rainfall. The biometric observation on yield attributes and grain yield were recorded. Water use and economics were also worked out.

Yield attributes
The results on yield attributes (Table 1) revealed that SRI showed a favorable influence on all the yield attributes of rice during all the years of study. Adoption of SRI recorded an average of 611 tillers m -2 which was 16.8 per cent higher than that of conventional method of rice cultivation (523). Higher number of grains panicle -1 was also associated with SRI than farmer's practice of rice cultivation. SRI registered a mean of 213 grains panicle -1 while it was only 180 in conventional method. Similar results of higher yield attributes with SRI than conventional method was reported by Senthil Kumar (2002) and Veeraputhiran et al. (2010). Agronomic evaluation studies of SRI conducted at Godavari delta regions indicated higher values of root weight and root volume in all the varieties studied under SRI than conventional method of rice cultivation (Raju and Sreenivas, 2008). In the present study also higher root volume and root weight under SRI might have absorbed more nutrients and water which inturn improved the production of more tillers and filled grains. This could be the reason for higher yield attributes under SRI. The yield attributes of rice viz., number of productive tillers m -2 , panicle length, number of filled grains per panicle and 1000 grain weight were higher under SRI than conventional method in Kurnool of Andra Pradesh which was observed by Krishnaji et al. (2008).

Grain yield
The grain yield of rice was substantially increased during all the period of experimentation due to adoption of SRI (Table.2). SRI registered a mean grain yield of 5633 kg ha -1 which was 24.0 per cent higher than conventional method of rice cultivation (4542 kg ha -1 ). Veeraputhiran et al. (2008) also obtained 23.1 percent yield improvement under SRI than farmers practice in Tamirabarani Command areas in Thirunelveli district of Southern Tamil Nadu. Higher yield attributes like number of productive tillers m -2 , and number of grains panicle -1 could be attributed for the production of higher grain  (Raju and Sreenivas, 2008).

Water use studies
The water use studies of both the rice cultivation methods (Table.2) clearly indicated the beneficial effect of SRI in terms of water saving and higher Water Use Efficiency (WUE). The total water use of rice including effective rainfall was drastically reduced (1055 mm) due to intermittent and alternate wetting and drying type of irrigation under SRI which was lesser than that of farmers practice (1370 mm).Thus, a substantial quantity of water saving by 24.3 per cent over the four years of study was evident due to the adoption of SRI. The higher grain yield coupled with enormous water saving under SRI method resulted in higher WUE of rice in the study area. The mean WUE of SRI was 5.33 kg ha mm -1 and it was only 3.29 kg ha -1 mm -1 in conventional method. Similar water saving and higher water use efficiency under SRI was also observed by Veeraputhiran et al. (2008) in Thirunelveli District of Southern Tamil Nadu. Similarly SRI required three and six irrigations lesser than normal transplanted rice during summer and kuruvai seasons respectively which was documented by Geethalakshmi et al (2009). Raju and Sreenivas (2008) also observed 40 per cent lesser water requirement (1025 mm) along with higher WUE of 6.18 kg ha mm -1 in intermittent flooding in SRI as against 1482 mm with WUE of 3.79 kg ha mm -1 under continuous flooding.

Economic analysis
The economic feasibility of both the method of rice cultivation ( Table.2) revealed that the cost of cultivation was comparatively lesser in SRI than that of conventional method. The mean cost of cultivation over the study period for SRI and conventional method was Rs. 21,020 ha -1 and Rs. 23,637 ha -1 respectively. Adoption of SRI was found to reduce the cost of cultivation by Rs.2517 ha -1 . In addition, higher gross income, net income and benefit cost ratio were also associated with SRI than conventional method of rice cultivation. Averaging the four years of study, SRI registered a total income of Rs.56,881 ha -1 and net income of Rs.35, 861 ha -1 as compared to Rs.46,158 ha -1 and Rs. 22,521 ha -1 respectively under conventional method. Regarding Benefit-Cost ratio (BC ratio), higher BC ratio was also associated with SRI (2.69) than conventional method (1.95). Lesser cost of cultivation coupled with higher gross and net income under SRI resulted in additional economic benefit over farmers practice. Adoption of SRI gained an additional net profit of Rs.13,340 ha -1 as compared to conventional method of rice cultivation. The economic superiority of SRI as compared to farmers practice of rice cultivation was also documented by Veeraputhiran et al. (2008). The results of the field experiments at Bhadra Command areas of Banglore showed that monetary benefits in terms of net return and benefit cost ratio were superior in SRI than conventional transplanting method (Hugar et al., 2009) . In the field study at Patna the highest net returns of Rs.34,706 ha -1 was obtained under SRI whereas the lowest returns (Rs.13,726 ha -1 ) was recorded under farmers' method (Singh and Batta, 2008).
Thus the results of the On-farm demonstrations clearly indicated that adoption of SRI lead to 24.0 per cent higher yield, substantial water saving (24.3 per cent), higher water use efficiency and better economic benefits which will pave way for sustainable rice production and higher standard of living of the farming community of the Manimuthar sub basin study area.