Weeds can reduce upland rice yields in coastal sandy area. Density and growth of weeds can be controlled and reduced by an intercropping system between upland rice with soybeans. The study aimed to determine the weeds composition change and weeds biomass in various crop proportions of upland rice and soybean under intercropping. The research was conducted from December 2016 until March 2017, at coastal sandy soil of Samas, Bantul, Yogyakarta (8°00’03.5”S and 110°15’20.1”E). This study used a complete randomized block design (RCBD) with one factor and three replications. The treatments were crop proportions of upland rice and soybean under intercropping with 6 levels, such as 100:0 (upland rice monoculture), 80:20, 60:40, 40:60, 20:80, and 0: 100 (soybean monoculture). The results showed that there was weeds composition changes due to setting crop proportions of upland rice and soybean under intercropping at coastal sandy soil. Weed of sedges, grass, and broadleaf were found throughout the experimental plots, but varied in number and type of weeds among experimental plots. Weeds condition differed among the soybean proportion treatments &lt; 40% and  ≥ 40%. The average community coefficient value was &lt;75% which was dominated by Digitaria nuda and Eragrostis tenella under soybean proportion treatments &lt; 40%, and Ludwigia parviflora and Amaranthus lividus under soybean proportion treatments ≥ 40%. The linear model was established between the increase of soybean proportion to a decrease in dry weight of weeds as Y = -0.6624X + 67.699; R2 = 0.7224).<br /><br />Keywords: crops proportion, intercropping, weeds community<br /><br />

ABSTRACT This research purposes know the growth and tubers yield of potato (G0) under various thickness of cocopeat media and time of sundstrom nutrient giving. The research was carried in the screen house in Pandansari, Paguyangan district from October 2014 until January 2015. The research used Randomized Complete Block Design with 2 factor and 3 repetitions. The first factor was the thickness of media with three levels; 10 cm, 15 cm, and 20 cm. The second factor was the time of nutrient solution giving with two levels; once for three days and once for six days. The results of the research showed that the thickness of cocopeat media 20 cm was good for plant height, total of leaves, wide of plant leaves, and improve the roots length 23.6 %. Time of nutrient giving once for three days was good for plant height, total of leaves, wide of plant leaves, weight of fresh plant, weight of dry plant and the result was good for stolon effectiveness (49.84%), weight of fresh tuber (137.85 g), and weight of dry tuber (21.55 g). The treatment of cocopeat medium thickness and time of nutrient giving had not been able to provide increased yield of potato tuber (G0).

Sandy coastal area in Indonesia is potential for upland rice cultivation, but it has constraints low of nutrient availability such as nitrogen. To solve the low fertility of the sandy land can be done by planting soybean between upland rice under intercropping system due to the soybean is able to provide nitrogen in soil through fixation of N2 in the air by root nodules. Intercropping is an alternative cropping system to increase land productivity, but there is competition between crops under an intercropping system. Reducing of the competition on the system is needed by crops proportion adjustment. The objective of the study is to examine growth and yield component of upland rice at different crops proportion under an intercropping system with soybean in the sandy coastal area. The research was conducted in Samas sandy coastal area, Bantul, Yogyakarta. This research used randomized complete block design (RCBD) with one factor and three blocks. The treatment of this research was five level crops proportion between upland rice and soybean under intercropping system, namely: 100:0; 80:20; 60:40; 40:60; and 20:80, respectively. The results showed that crop growth rate and yield per clump of upland rice increased on crops proportion adjustment under intercropping system with soybean. The crops proportion of 60:40 and 40:60 gave higher crop growth rates that were 1.45 g.dm-2.wk-1 and 1.44 1.45 g.dm-2.wk-1 than upland rice under monoculture (100:0) that was 1.09 g.dm-2.wk-1. The higher crop growth rates in crops proportion of 60:40 and 40:60 were able to give better yield per clump than other that were 17.17 g and 16.46 g, respectively. The yield of upland rice was not different under crops proportion of 100:0, 80:20, and 60:40 and decreased of upland rice proportion until ≤ 40% affected the low yield of upland rice.

<p>Fertilization of N, P, and K on soybean planted under <em>K</em><em>ayu Putih</em> stands to serve to increase soil nutrients. <em>Lithic Haplustert</em> is a subgroup of Vertisol with a relatively low fertility and organic matter with a heavy clay texture. This research aims to determine the response of soybean to the application of N, P, and K fertilizers on the <em>Lithic Haplustert</em> in physiology and yield. This research was conducted from February to May 2015 in the Srikoyo hamlet, Menggoran village, Playen district, Gunungkidul regency, Yogyakarta. The experimental design is split-split plot with three levels of fertilization of N (0, 25, 50 kg urea ha^-1), P (0, 150, 300 kg SP-36 ha^-1), and K (0, 75, 150 kg KCl ha^-1). The results showed that the application of 50 kg urea ha^-1and 300 kg SP-36 ha^-1 can increase the leaf area and photosynthesis rate. Dosage 150 kg KCl ha^-1 fertilizer increased the concentration of N, P, and K in the plant tissues significantly.</p>

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