Abstract:
Soil acidity is one of the most important soil factors affecting crop growth and ultimately
yield and profitability of coffee in Mbozi District Tanzania. Soils tend to be naturally
acidic in areas where rainfall is sufficient to cause substantial leaching of basic ions such
as calcium and magnesium, which are replaced by hydrogen ions. Most soils in Mbozi
District are acidic due to high rainfall and/or the use of soil acidifying fertilizers over a
long period of time. Low soil pH causes aluminium and manganese toxicities while
calcium, phosphorus and magnesium become deficient. In order to counteract the
situation, liming is inevitable. This study was conducted on Ultisols of Mbimba sub-
station, located in Mlowo Ward, Mbozi District, Songwe Region Tanzania. The study area
is located within latitudes 9 0 05’35.97”S and 9 0 05’13.10”E and longitudes 32 0 57’14.51”E
and 32 0 57’22.32”E. The area experiences mean annual rainfall ranging between 1 000 and
1 500 mm with a monomodal distribution pattern. The study aimed at increasing soil
productivity for coffee through the use of agricultural lime and ultimately improve
livelihoods of the coffee farmers in Mbozi District. Different levels of dolomite lime at 0
kgha -1 , 1 000 kgha -1 , 2 000 kgha -1 and 2 500 kgha -1 were used whereby NPK (22.6.12
+3S) at 150 kgha -1 was used at basal application rate. The field layout was set in a
randomized complete block design with three replications. The results indicated that lime
at 1 000 kgha -1 and 2 000 kgha -1 increased soil pH between 0.22 and 0.97 units and the
increase of P was significant at P<0.001. Lime applied at a rate of 2 000 kgha -1 increased
available P concentration by 5.73 - 7.28 mgkg -1 while exchangeable Potassium
concentration increased by 0.14 - 6.01mgkg -1 in all 3 levels of lime and K increase was
significant at P = 0.05. Soil Ca and Mg increased between 0.19 and 6.82 cmol(+)kg -1 and 0.54 - 1.98 cmol(+)kg -1 respectively after application of dolomitic lime. Plant height
increased between 60.4 and 67.1 cm, branches between 29-31, internodes between 23 and
27, canopy width between 74.7 and 79.5cm and stem girth between 8.2 and 9cm. A very
strong positive correlation was found between lime and Mg (R 2 = 0.8643), moderate
positive correlation between lime and N (R 2 = 0.4453), between lime and P (R 2 = 0.7064),
between lime and K (R 2 = 0.4043), between lime and Ca (R 2 = 0.5288) while weak
correlation between lime and Na (R 2 = 0.2007. Correlation value of < 0.4 is considered as
weak, 0.4 - 0.8 moderate correlation and 0.8˃ as very strong correlation. Thus, the study
recommends the use of 2 000 kgha -1 of CaMg(CO 3 ) 2 lime to be used by Mbimba Mbozi
farmers in coffee farms.
