The prominent issue faced by the farmers of Cauvery Delta regionin Tamil Nadu particularly Tiruchirapalli District is the lack of timely release of water for rice nursery preparation and transplanting. Hence wet seeding of rice is recommended for timely cultivation. On the other hand, sodic nature of the soil warrants rice cultivation only. Therefore, the present investigation was carried out to study the different soil and crop management practices on alleviating sodicity stress and improving rice (variety ADT 3) productivity under water-scarce conditions. The experiment was laid in a split plot design with six mainplots,including rice wet seeding, daincha (Sesbania aculeata) application as green manure, anti-oxidant microbial consortia (AOMC) spray and four sub-plots with graded levels of NPK based on soil test values with three replication. Results showed that the daincha incorporation @ 6.25 t/ha followed by rice wet seeding + AOMC spray @1.5 % with 125 % soil test based NPK had significantly increased thechlorophyll content, SPAD values, proline content and grain and straw yields which remained on par with daincha incorporation @ 6.25 t/ha followed by rice wet seeding + AOMC spray @1.5 % with 100 % soil test based NPK.Significantly lower ESP at 5% level and higher phosphatase activity in soil was also recorded by daincha incorporation @ 6.25 t/ha followed by rice wet seeding + AOMC spray @1.5 % with 125 % and 100 % soil test based NPK. Gross return, net return and B:C ratio were also higher in the plot, which received daincha incorporation @6.25 t/ha followed by rice wet seeding + AOMC spray @1.5 % with 100 % soil test based NPK. The present study reveals that the inclusion of ectophytic microbial population spray in rice plants and the management practices helps the crop to tolerate the sodicity stress under water-scarce condition by maintaining required physiological functions like proline synthesis and enzyme activities etc which need to be further explored at the genotypic level.

A long-term field experiment conducted since 1972 on Vertic Ustropep indicated that application of 10 t ha-1 of farmyard manure along with 100 per cen NPK recorded significantly lower bulk density. Farm yard manure application wit 100 per cent inorganics increased the hydraulic conductivity, water stable aggregates porosity and water holding capacity. There was increase in CEC, organic carbon an total N content of soil due to incorporation of organics with inorganics. There wa no marked changes in soil pH and EC due to various treatments. Available major and micronutrients increased significantly when organics was incorporated along with inorganic sources of nutrients

An incubation study on the dissolution of rock phosphates with soils of different pH, was taken up at Tamil Nadu Agricultural University, Coimbatore. It was concluded from the experiment that the dissolution of Udaipur rock phosphate and Mussorrie rock phosphate were remarkably higher in soils with a pH of 5.8 both at 30 and 60 day of incubation, followed by neutral soil (pH 7.6) and saline soil (pH 8.75).During the initial stage of incubation upto 30 days, the dissolution was found to be higher with Udaipur rock phosphate, whereas at the end of 60 days, Mussoorie rock phosphate recorded higher dissolution.

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A study was taken up in the existing Long Term Fertiliser Experiment in Tamil Nadu Agricultural University, Coimbatore, conducted since 1972, to study the status and content of various nitrogen fractions both organic and inorganic and the effect on crop yield, uptake by crops and availability of nitrogen in the soil. Exchangeable NII,-N and NO,-N were significantly increased by incremental additions of N. Inclusion of FYM along with inorganic fertilisers, had a positive effect on the buildup of all the organic N fractions. Path analysis revealed that hydrolysable NH-N was the principal fraction for yield prediction in case of finger millet, unidentified hydrolysable -N for erop N uptake and nitrate N to predict the available N in the post harvest soil samples after finger millet.

The monocropping of rice in the Deltaic zone deteriorates soil health and crop productivity. Seaweeds are marine resources easily available at negligible cost and also rich in bioactive compounds. A field experiment was conducted at Cauvery Delta zone of Tamil Nadu during summer season2021 to evaluate the bio-efficacy of Seaweed extract on growth, yield, and soil properties of rice, Oryza sativa var. ADT53. The experiment was framed in RBD comprising of 12 treatments viz., soil application of Seaweed extract(SWE) @ 12.5kg/ha,25kg/ha, 37.5kg/ha , foliar spraying of SWE gel & liquid @ 0.5% twice at tillering and panicle initiation stages, a combination of soil application and foliar spray and fertilizer alone. Experimental findings revealed that the soil application of SWE  @ 12.5kg/ha along with a foliar spray of seaweed liquid recorded higher plant height (121.1cm),dry matter production (11390kg/ha),yield attributes viz., number of grains per panicle (166), panicle length (21.8 cm), thousand grain weight (14.7g), number of productive tillers per m2 (275), grain yield (5612 kg/ha)and straw yield (7829 kg/ha). However, The soil application of SWE @ 25kg/ha recorded higher soil available nutrients viz.,N(260 kg/ha);P(42kg/ha); K(170kg/ha);Ca(27.7meq/100g); Mg(5.5meq/100g);S(18.2mg/kg);Zn (1.17ppm); Fe (33.82ppm); Cu(1.61ppm);Mn(18.97ppm).The study will help sustain rice productivity and soil fertility in the deltaic zone of Tamil Nadu. The soil application of seaweed extract @ 12.5kg/ha along with foliar spraying (0.5% twice) could be a promising option in the rice ecosystem.

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