DIRECT AND RESIDUAL EFFECT OF SLUDGE AND OTHER PHOSPHORUS SOURCES ON FLUORINE CONTENT IN PADDY AND COWPEA UNDER SEQUENCE

摘要

An investigation on direct and residual effect of sludge and other Phosphorus sources on fluorine content in paddy and cowpea under sequence conducted at Agricultural Research Station (Paddy), Sirsi, Dharwad. Fluorine content of paddy grain was increased wherever higher levels of sludge applied. Higher fluorine content was recorded with 100 percent sludge P (7.01 & 6.84 ppm ) during 1999 and 2000 and was on par with 75 percent sludge + 25 percent SSP with (6.41 & 6.38 ppm) and without P-solubilizer (6.33 & 6.30 ppm) and 100 percent sludge with RDFYM( 6.40 &6.42 ppm). The fluorine content of grain was significantly reduced with 50 percent sludge +50 percent SSP+ P-S (3.81 & 3.77 ppm) during 1999 and 2000, respectively. Application of 25 percent sludge + 75 percent SSP with (3.60 & 3.70 ppm) and without P- solubilizer (3.625 & 3.63 ppm) was on par with 100 percent RP (3.73 & 3.80 ppm) and 100 percent SSP with (3.51 & 3.57 ppm) and without (3.61 & 3.69 ppm) P-solubilizer during 1999 and 2000, respectively. Similar effect was also noticed with respect to fluorine content in straw of paddy. However, fluorine content in straw was marginally higher than grain. Residual effect of sludge and other P sources revealed that fluorine content of cowpea grain was low compared to paddy grain. However, significantly higher fluorine content was recorded with 100 percent sludge ( 3.42 ppm) over other treatments and was on par with 75 percent sludge + 25 percent SSP with (3.4 ppm) and without P-S (3.35 ppm), 100 percent sludge +P-S (3.4 ppm) and 100 percent sludge with different levels of RDFYM (3.42,3.38 & 3.30 ppm), respectively. Fluorine content in grain was significantly low with application of 100 percent SSP (2.25 ppm) and 100 percent RP (2.43 ppm) and were on par with 25 percent sludge + 75 percent SSP (2.40 ppm). Application of sludge and other P sources with P -solubilizer decreased fluorine content marginally . Similar effect was also noticed on fluorine content in haulm of cowpea. However, fluorine content in grain was less compared to grain.