Root respiration interferes with peat CO2 emission measurement

Fahmuddin Agus, Etik Handayani, Meine van Noordwijk, Kamarudin Idris, Supiandi Sabiham

Abstract

Root respiration and microbial decomposition release CO2 from peatland. Mixture between these two measurements causes an over-estimation of greenhouse gas contribution, because CO2 produced by the former is offset by atmospheric CO2 removal during photosynthesis. We separated the two components by measuring, from closed chambers, the CO2 emission from the rooted (R) and non-rooted (NR) zones of peatland planted to oil palm. Three pieces of roots were channelled through a 5 cm hole into each of the grounded part of the R chamber. Emitted CO2 was captured by 30-cm diameter and 30-cm tall PVC gas chambers, sampled using 10 ml syringes, and measured using gas chromatography. The measurements were conducted in Aceh, Sumatra in the early rainy season (Oct-Nov 2008). We found that CO2 emitted from the NR chambers was about 62% of that of the R chamber, indicating a significant contribution of the root in producing CO2. The average amount of emitted CO2 from these 1, 5 and 10 year oil palm soils ranged from 18 to 24 t/ha/yr. Capturing both the R and NR zones in CO2 emission measurement is advisable, but under limited resources, the NR zone should be prioritised.

Key Words:
Peat, root respiration, microbial decomposition, CO2 emissions

Paper presented at 19th World Congress of Soil Science, Soil Solutions for a Changing World. 1-6 August 2010. Brisbane. Australia. Published on DVD.

Nutrient Balance and Vegetable Crop Production
as Affectedby Different Sources of Organic Fertilizers

Fahmuddin Agus, Diah Setyorini, Wiwik Hartatik^, Sang-Min Lee,
Jwa-Kyung Sung, and Jae-Hoon Shin

ABSTRAK

Understanding the net nutrient balance in a farming system is crucial in assessing the systems sustainability. We quantified N, P and K balances under vegetable organic farming in a Eutric Hapludand in West Java, Indonesia in five planting seasons from 2005 to 2007. The ten treatments and three replications, arranged in a completely randomized block design, included single or combined sources of organic fertilizers: barnyard manure, composts or green manures. The organic matter rates were adjusted every planting season depending on the previous crop responses. The results showed that the application of 20 t ha^-1 barnyard manure per crop resulted in positive balances of N, P, and K, except in the second crops of 2006 where potassium balance were -25 to -11 kg ha^-1 under the treatments involving cattle barnyard manure, because of low K content of these treatments and high K uptake by Chinese cabbage. Application of 20 to 25 t ha^-1 of plant residue or 5 t ha^-1 of Tithonia compost also resulted in a negative K balance. Soil available P increased significantly under 25 t ha^-1 barnyard manure and that under chicken manure had the highest available P. Accordingly, chicken barnyard manure gave the highest crop yield because of relatively higher N, P and K contents. Plant residues gave the lowest yield due to the lowest nutrient content among all sources. Reducing the use of barnyard manure to 12.5 t ha^-1 and substituting it with Tithonia compost, Tithonia green manure or vegetable plant residue compost gave insignificantly different yield compared to the application of 25 t ha^-1 barnyard manure singly. In the long run, application of 25 t ha^-1 cattle, goat, and horse manure or about 20 t ha^-1 chicken manure is recommendable for sustaining the fertility of this Andisol for vegetable production.

Key words: Nutrient balance, vegetable crops, barnyard manure, organic farming, Andisol
Papers published in Korean Journal of Soil Science Fertilizer. 42 (1). 1-13 (2009)