Abstract:
Phosphorus fixation, which is responsible for low availability of P, is one of the major problems
of crop growth in acidic soils such as LS. Therefore, the incubation study was conducted to
determine the suitability of SCG as soil amender to reduce P fixing capacity of LS.
LS samples were collected from three different Karsa areas at depth of 0-15 cm using soil auger
and SCG samples were collected from eight coffee houses at Jimma Town. Treatment soils
containing 0, 20, 60 and 180 mg/L were prepared from KH2PO4.25 ml portions of the treatment
solutions were added to 2 g of LS samples and LS +SCG (2:0.25, 2:0.5, 2:0.75 and 2:1) in cups
and were plugged respectively. The samples were incubated at room temperature and allowed to
stand for 1, 3, 7, 14 and 28 days respectively. At the set days, the fixed P was determined using
of Ascrobic Acid method. The amount of P recovered at different incubation periods increased
with increasing a dose of SCG addition. The study revealed the percentage of organic carbon
contents in both LS and SCG were as follows: LS (2.106%) < (47.95%). pH of LS (5.61) < pH of
SCG (7.21) and available P of LS (41.91 mg/kg) < SCG (1745 mg/kg). The fixed decreased with
added a dose of SCG throughout the incubation period in mixture of LS and SCG. The LS
blended with SCG showed a less P fixing capacity between 60-66% as compared with LS which
shows high P fixing capacity between 92-99%. Less than 63% of P fixation in the mixture of LS
and SCG was decreased after one day of incubation.
Application of SCG is recommended for LS to increase soil fertility. Organic carbon and
available P could therefore be responsible in minimizing of P fixation of LS
