Leaf and pod insect pests are important on soybean (Glycine max L.) in Indonesia, causing loss of seed production. The study was carried out to evaluate the potential of water crude extract mixture of Azadirachta indica seed, Cymbopogon nardus plant and Alpinia galanga rhizome to control leaf and pod insect pests on soybean. The study was conducted in the organic farming system cultivation of soybean and it was arranged with Randomized Block Design. The concentrations of crude extract were 5, 10, 20 and 40% (v/v) applied on soybean. The result showed that crude extract significantly affected on the damages of leaf and pod caused by the insect pest and seed production. The 20 and 40% of extracts concentrations resulted in 16.07 and 14.97% leaf damage caused by insect, pod damage of 5.38 and 5.33% and 7.56 and 6.77% caused by sucking insect and pod borer insect, respectively. Those concentrations yielded 436.0 and 540.6 g of seed production/3m 2 plot size, respectively. This study showed that the mixture of crude extracts has the potential to be used in controlling insect pests on soybean.

This research was carried out at the PTPN III Sarang Giting plantation, Afdeling II, which is located in Sarang Giting Village, Dolok Masihul District, Serdang Bedagai Regency, North Sumatra Province. Venue Altitude 30m above sea level (asl) and flat land topography.    The purpose of this study was to determine the effect of stem circumference and production of rubber plants (Hevea brasiliensis Muell. Arg) on ​​potassium (KCl) combined with agricultural lime (CaCO3) and magnesium (MgSO4) and their effect on the dynamics of soil K levels. This study used a factorial randomized block design (RBD) with 3 (three) factors studied, namely the agricultural lime application factor (C), which consisted of C0 = control and C1 = 1500g/tree/year. The second treatment factor was giving magnesium (M) which consisted of M0 = control, M1 = 1500g/tree/year, M2 = 3000g/tree/year, and M3 = 4500g/tree/year. The third treatment factor was the provision of potassium (K) consisting of K0 = control, K1 = 500g/tree/year, K2 = 1000g/tree/year, and K3 = 1500g/tree/year. The results showed that the administration of potassium combined with the application of agricultural lime and magnesium had a significant effect on the growth parameters of stem circumference. Potassium application combined with agricultural lime and kiserite also had a significant effect on the dynamics of K levels in the soil. However, it did not significantly affect the production of liquid latex

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