Global demand for food has always been on the increase due to the increase of the population in this world. Intercropping is one of the alternatives of agronomic practices that is widely practiced in ensuring food security and enhancing yield stability. Strip, mixed, and relay intercropping can be practiced to increase crop production. In addition to achieving a successful intercropping system, factors such as suitable crops, time of sowing, maturity of the crop, and plant density need to be considered before and during planting. Besides, practiced intercropping becomes a useful cropping system to increase efficient resource utilization, enhance biodiversity, promote soil health, enhance soil fertility, erosion control, yield advantage, weed, pest, and disease control, insurance against crop failure, ecosystem and modification of microclimate, market instability, and increase farmers income. Crop productivity in any types of cropping system implemented relies primarily on the interception of photosynthetically active radiation (PAR) of crop canopy and conversion of intercepted radiation into biomass or known as radiation use efficiency (RUE). Both PAR and RUE are important measurements that have significant roles in crop growth and development in which the accessibility of these radiation dynamics is connected with the leaf area index and crop canopy characteristics in maximizing yield as well as total productivity of the crop component in intercropping systems.

Pendahuluan: Penelitian ini bertujuan untuk mendapatkan dosis yang sesuai dari limbah kotoran sapi, kapur kalsium oksida maupun interaksinya dalam meningkatkan pertumbuhan dan produksi tanaman kacang panjang. Metode Penelitian: Penelitian dilaksanakan di Desa Secanggang, Kecamatan Secanggang, Kabupaten Langkat pada Juni-September 2017. Penelitian ini menggunakan Rancangan Acak Kelompok Faktorial, faktor pertama (limbah kotoran sapi) dosis L0 = 0 ton/ha; L1 = 10 ton/ha; dan L2 = 20 ton/ha. Faktor kedua (kapur kalsium oksida) dosis K0 = 0 ton/ha; K1 = 3 ton/ha; K2 = 6 ton/ha; dan K3 = 9 ton/ha. Data dianalisis uji F dan dilanjutkan uji DMRT 5% menggunakan software IBM SPSS Statistic v.20. Hasil Penelitian: Limbah kotoran sapi dosis 10-20 ton/ha signifikan meningkatkan tinggi tanaman umur 4 Minggu Setelah Tanam (MST) dan produksi tanaman/plot kacang panjang masing-masing berkisar 2,14-2,50% dan 13,00-15,98%, serta dosis 20 ton/ha signifikan meningkatkan produksi tanaman/sampel sebesar 17,44% dibandingkan kontrol. Aplikasi kapur kalsium oksida dosis 9 ton/ha signifikan meningkatkan tinggi tanaman kacang panjang pada umur 4 MST sebesar 2,46%, dan dosis 6-9 ton/ha siginifikan meningkatkan produksi tanaman/sampel dan produksi tanaman/plot, namun tertinggi terdapat pada dosis 6 ton/ha masing-masing sebesar 13,51% dan 20,16% dibandingkan kontrol. Interaksi limbah kotoran sapi dengan kapur kalsium oksida berpengaruh tidak nyata terhadap pertumbuhan dan produksi kacang panjang.

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