THE CORRELATION OF ELEVATION, SOIL CHEMICAL PROPERTIES AND YIELD OF COFFEE ARABICA IN SHADED CONDITIONS.

The research aims to analyze the correlation of altitude, soil chemical properties and shades on Arabica coffee yields in Humbang Hasundutan Regency Sumatera Utara Province. This research was conducted using survey method with purposive sampling approach. Sampling were conducted on altitude varied between 1200 – 1500 m asl. Soil samples in top soil and sub soil were taken in order to analyze pH, C, N, P2O5, K, and cation exchange capacity (CEC). Coffee plant growth variables observed including productive branches, number of bunches, number of fruit per bunches, diameter of canopy and total yield. Whereas the quality variable measured were physical quality and taste. Data on soil chemical properties, elevation, yield and coffee quality were analyzed using the correlation method. The results showed that under shaded condition, N, CEC, pH, K and P were positively correlated with height increase, while C-organic, productive branches, number of fruits per bunch and coffee production were negatively correlated. Whereas in the condition without shade, N, C, pH, K, productive branches, the number of fruit per bunch is negatively correlated with height increase, while CEC, P, number of bunches, diameter of canopy and coffee yield are positively correlated. Statistical data shows that under shaded condition, the strongest correlation showed by pH and P av (0.999), Whereas in an unshaded condition, yield and CEC showed the strongest correlation (0.994). [ABSTRACT FROM AUTHOR]