Thesis Abstract of AGS Students

Supha Randhawa (1988)

Stratifications of upland rainfed areas in Chiang Mai based on the similarity of climate and soil characteristics was conducted in order to guide agricultural planning and transfering technology. The study area covers 544,375 rais of upland rainfed agricultural land with the altitude of 300-500 metres above mean sea level in the districts of Fang, Chiang Dao, Phrao, Mae Taeng, Mae Rim, San Kham Phaeng, San Sai, Doi Saket, Hang Dong, San Pa Tong, Chomthong and Hod which consist of 11 major soil series in 32 operational taxonomic units (OTU).

Euclidean distance coefficients approximating soil-climate similarity were calculated for 32 OTU using 12 attributes of climate and soil namely, length of growing period, pracipitation during growing period, the maximum probability of ten day dry spell two months after the start of rain, available water holding capacity of soil, soil pH for upper and lower depth, texture for surface and sub soil, organic matter, cation exchange capacity, available phosphorus, available potassium and average temperature during growing period. The coefficients were sorted into clusters by average linkage between groups method. Four recommendation domains were identified, each having different production potential and stability.

Group I is the most predominant group. It was found that 31, 21, 12, 9, 6, 6, 4, 3, 3 and 2 percents of the uplands in this group lie in Fang, San Kham Phaeng, Chiang Dao, Hod, Phrao, Mae Taeng, Mae Rim, Doi Saket, San Sai, and Hang Dong, respectively. This group has low production potential and is suitable for monocropping. Production potential may be increased by practising relay cropping or intercropping systems. Main crop can be either short or long duration crops. Because of low soil fertility, soil improvement is necessary for stabilizing yield level. This group shows relatively high stability due to low probability of ten-day dry spell during the growing period.

Group II has the lowest production potential, approximately 73, 15, 7 and 3 percents of the uplands in this group are distributed in San Pa Tong, Chom Thong, Hang Dong and Mae Taeng, respectively. Monocropping of short duration crops, or crops which require low water consumption and are drought tolerant are suitable for growing on this group of land. In some operational taxonomic units that have intermediate growing period, especially in OTU 7, 8, 9 and 13, double cropping of early varieties may be on-farm tested. The arrangement of cropping pattern and turn around period should be coincided with the dry spell period during the growing season. This group has low soil fertility. Stability of the system is low because of high probability of ten-day dry spell during the growing period.

About 54, 26, 9 and 9 percents of land in Group III was found in Phrao, Fang, San Sai, Mae Taeng, respectively. Production potential is higher than Group I and Group II. Double cropping is possible for this group. Due to its low soil fertility, incorporation of legume in the cropping systems is recommended for improving soil. System stability is high due to low probability of ten-day dry spell during the growing period.

The distribution of uplands in Group IV in Chiang Dao, Doi Saket, Fang and San Kham Phaeng was found to be 59, 30, 6 and 3 percents, respectively. Double cropping may be practised on this group of land. Possible cropping systems can be similar to those in Group III. Relatively high productivity is expected from this group of land due to its inherent soil fertility. System stability is similar to Group III.

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