Eko Hanudin

Universitas Gadjah Mada Indonesia
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The diversity and physiological activities of weeds in land cultivated with various corn cultivars and fertilized with various nitrogen doses

Abstract. Rahayu M, Yudono P, Indradewa D, Hanudin E. 2019. The diversity and physiological activities of weeds in land cultivated with various corn cultivars and fertilized with various nitrogen doses. Biodiversitas 20: 622-628. Both weeds and corn have nutrient needs. Nitrogen is one of the essential elements required by weeds and corn. Each corn cultivar and weed also has different ability to absorb nitrogen. This study aimed to determine the effect of corn cultivar and nitrogen dose on the diversity and physiological activities of weeds. The research was conducted in Banguntapan, Bantul, Yogyakarta from December 2016 to May 2017. The study used a completely randomized block design with 2 factors with three replications. The first factor was corn cultivar, consisting of four cultivars (Bisi 18, NK 33, DK 95 and Sukmaraga) and the second factor was the nitrogen dose, consisting of three levels (25 kg N ha-1, 150 kg N ha-1 and 275 kg N ha-1). The data were analyzed using 5% variance analysis and continued with Duncan test at 5% level. The results showed that the most commonly found weeds were broadleaves, but the most dominant weed was a grass, namely Dactyloctenium aegyptium, except Sukmaraga with nitrogen doses of 25 kg ha-1 and 150 kg ha-1 in 4 weeks after planting (WAP). In 8 WAP, weeds that grew in land planted with all combinations of cultivars and nitrogen doses were Cyperus rotundus, Dactyloctenium aegyptium, Digitaria ciliaris, Eleusine indica, Eragrostis tenella, Amaranthus spinosus, and Richardia scabra. There were no significant differences on the nitrate reductase activity, chlorophyll content, leaf area index, and dry weight among cultivars. The treatment of 25 kg N ha-1 resulted in the lowest leaf area index and total chlorophyll content, but the highest nitrate reductase activity.

Indian Journal Of Agricultural Research

Soil morphogenesis diversity at the southern flank of Merapi Volcano, Indonesia five years post-eruption

This study aims to find out the soil morphology diversity at the southern flank of Mt.Merapi Yogyakarta, Indonesia. The field research was conducted using purposive sampling method where each site of geomorphological unit as representing of the cone, upper, middle and lower slopes of Mt.Merapi. Poligenesis of the soil morphology was observed at pedon P1 with composition of the upper and buried soil was Typic Hapludands-Typic Hapludands, P3 (Andic Eutrudepts-Vitrandic Udorthents), P4 (Vitrandic Udorthents -Typic Hapludands), and P5 (Andic Eutrudepts-Andic Eutrudepts). Whereas the monogenesis of the soil morphology was observed at pedon P2, P6, P7 and P8 with subgroups of Typic hapludands, Andic Eutrudepts, Andic Dystrodepts and Typic Udorthents, respectively. Soil morphogenesis diversity (polygenesis) shown by the presence of a pedon having more than one soil profile was not a limiting factor for crop roots growth, so the agro-ecosystem recovery process was relatively fast.

Methane production potential of soil profile in organic paddy field

The use of organic fertilizers in the organic paddy/rice field can increase methane (CH<sub>4</sub>) production, which leads to environmental problems. In this study, we aimed to determine the CH<sub>4</sub> production potential (CH<sub>4</sub>-PP) by a soil profile from samples using flood incubation. Soil properties (chemical, physical, and biological) were analyzed from soil samples of three different paddy farming systems (organic, semi-organic, and conventional), whilst soil from teak forest was used as the control. A significant relationship was determined between soil properties and CH<sub>4</sub>-PP. The average amount of CH<sub>4</sub>-PP in the organic rice field profile was the highest among all the samples (1.36 µg CH<sub>4</sub>/kg soil/day). However, the CH<sub>4</sub> oxidation potential (CH<sub>4</sub>-OP) is high as well, as this was a chance of mitigation options should focus on increasing the methanotrophic activity which might reduce CH<sub>4</sub> emissions to the atmosphere. The factor most influencing CH<sub>4</sub>-PP is soil C-organic (C<sub>org</sub>). C<sub>org</sub> and CH<sub>4</sub>-PP of the top soil of organic rice fields were 2.09% and 1.81 µg CH<sub>4</sub>/kg soil/day, respectively. As a consequence, here the mitigation options require more efforts than in the other farming systems. Soil with various amounts of C<sub>org</sub> reached a maximum point of CH<sub>4</sub>-PP at various time after incubation (20, 15, and 10 days for the highest, medium, and the lowest amounts of C<sub>org</sub>, respectively). A high amount of C<sub>org</sub> provided enough C substrate for producing a higher amount of CH<sub>4</sub> and reaching its longer peak production than the low amount of C<sub>org</sub>. These findings also provide guidance that mitigation option reduces CH<sub>4 </sub>emissions from organic rice fields and leads to drainage every10–20 days before reaching the maximum CH<sub>4</sub>-PP. 

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