The transmission of solar radiation and micro climate profiles and their relationship to growth and crop production of intercropping plants in several ages of coconut

Abstract

Potential of land in coconut plantations to support the program polyculture in Indonesia is very large, but the availability and suitability of the solar radiation distribution and microclimate is the main constraint. The purpose of research was to identify and analyzed the distribution of solar radiation, micro-climate profile, growth and production of intercropping crops, land productivity and economic viability of farming in some coconut ages. Research conducted in the coconut experimental garden Kima Atas, Indonesian Coconut and Palmae Research Institute (ICOPRI) Manado North Sulawesi in 2007-2009. Observation was conducted to identify the distribution of solar radiation, micro-climate and the distribution of rain on coconut age of 5, 20, and 50 years. Experimental studies were intercropping planting, ie maize, rice, and peanuts in coconut plantations and open fields. Solar radiation data observed by the method of moving using a light meter, temperature and air humidity were observed every day using digital termohigrograf and measurement of soil water content by gravimetric method. Intercropping crops data were observed on vegetative and production variables. Data were analyzed with statistic deskriptive, analysis of variance, BC and the land equivalent ratio. The research results show that the transmission of the highest solar radiation occurs at the age of 50 years of coconut (40%) and lowest in the age of 20 years (22%). The simulation results show that highest daily solar radiation temporal distribution in a rectangular plantation coconut cropping systems occurred at 12.00 and triangular systems are spread evenly throughout the day. Spatial distribution of solar radiation on a rectangular system of planting coconut placed in the broader region between rows of coconut in comparison with the triangular system. Air temperature in a plantation coconut 1-2°C lower than the temperature in the open air and moisture proifl otherwise. Air temperature in the coconut age 5 years was higher. Soil water content in coconut plantation age 20 years was higher (41%) compared with the coconut ages 5 and 50 years (21 and 24%). Rainfall interception in the canopy of coconut plantations age of 5, 20, and 50 years were 27, 38, and 29% respectively of the average rainfall that occurs when the observations. The highest average production of maize, rice, and peanut obtained in the age of 50 years of coconut but still lower than production in open fields. Empirical model of the relationship between the transmission of radiation at some ages coconut with production of maize, rice, and peanuts are logarithmic. Mathematical models for maize, rice, and peanuts were Ymaize=2.28ln(Rt)-5.42 [R2=0.99], Yrice= 2.17ln(Rt)-4.85 [R2 = 0.98], and Ypeanut=0.63ln(Rt)-2.01 [R2 = 0.84]. Land Equivalent Ratio (LER) were 1.62-1.80 it means that coconut plantation land productivity rose an average of> 60 with coconut farming polyculture systems. The coconut farming polyculture with maize, rice, and peanuts is economically feasible to be developed with the average BC ratio> 1.

Luas lahan kelapa potensial di Indonesia yang tersedia untuk menerapkan usaha tani polikultur kurang lebih 2.7 juta ha. Potensi ini diperoleh dari luasan pemilikan lahan perkebunan kelapa di tingkat petani sebesar 3.7 juta ha yang diusahakan secara monokultur ada sekitar 96% dan dari aspek agronomi tersedia 75% lahan yang tidak digunakan oleh sistem perakaran kelapa. Jika dihitung secara matematis, maka tersedia lahan kelapa monokultur sekitar 2.7 juta hektar yang berpotensi untuk usaha tani polikultur di Indonesia. Namun, Sistem tanam dan umur kelapa secara khusus akan mempengaruhi transmisi radiasi matahari. Tujuan penelitian adalah untuk mengetahui pola transmisi radiasi matahari dan profil iklim mikro, distribusi hujan dan produksi beberapa tanaman sela yang dijadikan tanaman indikator pada beberapa umur tanaman kelapa. Penelitian telah dilaksanakan di Kebun Percobaan Kelapa, Balai Penelitian Tanaman Palma (Balit Palma) yang berlokasi di Kima Atas-Manado Sulawesi Utara. Metode penelitian yang digunakan menggabungkan penelitian observasi dan eksperimental. Metode penelitian bersifat observasi melalui pengukuran radiasi matahari, suhu udara, kelembaban, dan kadar air tanah di areal pertanaman kelapa yang berumur 5, 20, 50 tahun, dan di lahan terbuka di sekitar perkebunan kelapa. Pengamatan radiasi matahari hanya dilakukan pada saat cuaca cerah dengan menggunakan light meter, pengukuran suhu dan kelembaban menggunakan termohigrograf, penentuan kadar air tanah dengan metode gravimetri dan parameter distribusi hujan didapatkan alat yang terpasang permanen di tiga umur kelapa. Analisa data dengan statistik deskriptif dan regresi. Metode penelitian eksperimental adalah penanaman tanaman jagung, padi gogo, dan kacang tanah yang ditanam pada petakan yang diletakkan di antara barisan kelapa berjarak 1.5 m dari batang kelapa. Tiap jenis tanaman sela ditanam pada tiga petak pada tiap umur kelapa dan dan di lahan terbuka. Analisis data dilakukan dengan analisis ragam dan regresi . Penelitian eksperimental tergolong pada kegiatan usaha tani polikultur, sehingga perlu dilakukan analisis produktivitas lahan dan kelayakan ekonomi. Analisis produktivitas lahan dengan menghitung land equivalent ratio (LER), yaitu perbandingan antara tingkat produksi usaha tani monokultur dengan produksi usaha tani polikultur. Analisis ekonomi dilakukan untuk mengetahui kelayakan usaha tani kelapa polikultur dengan tanaman sela jagung, padi, dan kacang tanah di pertanaman kelapa umur 5, 20, dan 50 tahun dengan indikator nilai BC ratio.