Abstract
To amend physical properties of coastal saline soil for rice production, six biochar treatments (0, 0.5, 1, 2, 4 and 6 kg biochar per m(2) soil) were set up as CK, T1, T2, T3, T4 and T5, respectively and their effect on the biochemical properties of coastal saline soil and rice growth characteristics were evaluated in a barrel planting experiment. The results showed that compared with CK (with no biochar added), the soil EC of T1 and T2-T5 was reduced by 11.5 %, but increased by 8.8-62.9 %, respectively. The available potassium and organic matter contents of T1-T5 increased ranging from 3.7-10.2 % to 8.0-46.8 %, respectively. With the increase of the biochar amount, the urease activity of soil in the 0-10 cm deep soil showed an increasing trend by 194.8-744.6 % with T1-T5, compared with that of the CK treatment. The activity of alkaline phosphatase in soil increased first and then decreased, and its increment with T1-T5 was between 28.2 and 64.8 % in comparison with that of CK. With more biochar added to soil, the leaf dry weight, root dry weight, total dry matter mass, total root length, single panicle quality and weight per 100 grains showed a trend of increase first and then decrease. The highest incremental values of all measurements were obtained with T1 by 21.8 %, 23.9 %, 13.8 %, 33.9 %, 30.8 % and 11.6 % respectively, compared with those with CK. However, adding biochar in soil demonstrated insignificant effect on the weight of single panicle, panicle length, stem thickness, tillers, setting rate, soil hydrolyzable nitrogen, available phosphorus content, rice protein, amylose, and taste quality among all treatments. In summary, the application of 0.5 kg m(-2) biochar can improve the biochemical properties of saline soil and therefore increase rice yield.