The arranging of soybean planting pattern for micro climate modification

The experiment were conducted in Inlitkabi Muneng during Dry Season of 1996 and Rainy Season of 1996/97. The microclimate was developed according to 4 soybean planting pattern, ie. (1) soybean planting pattern of high population (500.000 plants/ha) planted in single row system (planting distance of 40x10 cm, 2 plants/hill); (2) soybean planting pattern of high population (500.000 plans/ha) planted in double row system (planting distance of 50 cm x (30 cm x 10 cm), 2 plants/hill; (3) soybean planting pattern of low population (250.000 plants/ha) planted in single row system (40 cm x 10 cm, 1 plant/hill); (4) soybean planting pattern of low population (250.000 plants/ha) planted in double row system (50 cm x (30 cm x 10 cm), 1 plant/hill). The treatments were arranged in randomized complete block design with 4 replications. The objective of the research was to improve microclimate environment suitable for soybean growth and production. The result indicated that the soybean growth during dry season had plants height of 35-41 cm and LAI of 1.7-4. There created large enough space between plant stands. During that growing season the air temperature was high (up to 36.7 deg. C in the day), the air humidity was low enough (35-73 percent) and high radiation created high evaporative demand. Therefore planting soybean in high population under lack of water during dry season was severe to drought. Planting in double row systems were create more open space between double rows, caused higher soil temperature with high fluctuation. Therefore planting in single row system during dry season would create better crop environment. The contrary situation was found in soybean planting during rainy season. The crops grew well (plant height + 86 cm) and the leaves covered each other (LAI of 7.9-8.3 in high population planting) created close space between plant stands and there were enough air circulation inside. This situation caused air temperature and humidity were not different between treatments. According to high LAI in soybean planting of high population caused more leaves were not effective to do photosynthesis. Therefore planting in double row system during rainy season would be more suitable./Penelitian dilaksanakan di Inlitkabi Muneng pada MK 1996 dan MH 1996/97. Untuk mengatur lingkungan iklim mikro, disusun 4 macam pola penanaman kedelai, yaitu (1) pertanaman kedelai dengan populasi tinggi (500.000 tnm/ha) yang ditanam dalam sistem baris tunggal (jarak tanam 40 cm x 10 cm, 2 tnm/rumpun); (2) pertanaman kedelai dengan populasi tinggi dan sistem tanam baris ganda (50 cm x 10 cm), 2 tnm/rumpun); (3) pertanaman kedelai dengan populasi rendah (250.000 tnm/ha) dan sistem baris ganda (50 cm x (30 cm x 10 cm), 1 tnm/rumpun). Petak-petak percobaan disusun mengikuti rancangan petak terbagi dengan 4 ulangan. Adapun penelitian ini bertujuan untuk mengkaji perubahan iklim mikro akibat perbedaan pola penanaman kedelai yang akhirnya diharapkan dapat diperoleh keadaan iklim mikro yang sesuai untuk pertumbuhan kedelai. Hasil penelitian menunjukkan bahwa dalam pertanaman musim kemarau, tinggi tanaman kedelai berkisar 35-41 cm dan ILD 1,7-4. Disini terdapat ruang yang cukup terbuka antar tanaman. Suhu udara yang tinggi hingga mencapai dasar tajuk mendorong terjadinya evapotranspirasi yang tinggi, sehingga penanaman dengan populasi tinggi di musim kemarau dengan ketersediaan air yang terbatas akan memperparah terjadinya cekaman air. Di samping itu penanaman dalam sistem baris ganda menciptakan ruang yang lebih terbuka antar tanaman sehingga menyebabkan suhu tanah menjadi lebih tinggi (1-5 der. C) dengan fluktuasi yang tinggi pula, selisih suhu tanah pagi dan siang hari mencapai 14,7 der. C. Oleh karena itu penanaman dalam sistem baris tunggal di musim kemarau dapat menciptakan lingkungan tumbuh yang lebih baik. Keadaan sebaliknya ditemui dalam pertanaman musim hujan di mana tanaman tumbuh lebat dengan tinggi tanaman + 86 cm dan ILD 7,9-8,3 pada populasi tinggi, menciptakan ruang antar tanaman yang relatif tertutup dan tidak terdapat sirkulasi udara yang cukup, sehingga suhu dan kelembaban udara di dalam pertanaman tidak berbeda antar perlakuan pola penanaman yang berbeda. Penanaman kedelai dalam populasi tinggi di musim hujan menyebabkan banyak daun tidak efektif melakukan fotosintesis karena ILD terlalu tinggi. Dalam keadaan ini penanaman dalam sistem baris ganda lebih menguntungkan.