تأثیر اندازه و عمق جایگذاری بقایای گیاهی بر دینامیک کربن و نیتروژن آلی

نوع مقاله : علمی - پژوهشی

نویسندگان

1 دانشگاه زنجان

2 دانشگاه جیرفت

چکیده

به­منظور بررسی تآثیر اندازه و عمق جایگذاری بقایای گیاهی بر دینامیک کربن و نیتروژن آلی، آزمایشی به­صورت کرت­های دوبار خرد شده در سه تکرار و در قالب طرح بلوک­های کامل تصادفی در مزرعه روی بقایای گندم (Triticum aestivum L.) به­روش کیف کلش اجرا گردید. فاکتورهای مورد بررسی شامل مدت زمان خوابانیدن بقایای گیاهی در چهار سطح (1، 2، 3 و 4 ماه)، عمق جایگذاری بقایای گیاهی در چهار سطح (5، 15، 30 و 45 سانتی­متر) و اندازه بقایای گیاهی در سه سطح (2/0 تا 5/0، 1 تا 2 و 5 تا 10 سانتی­متر) بودند که به­ترتیب در کرت­های اصلی، فرعی و فرعی- فرعی قرار داده شدند. پس از سپری شدن فواصل زمانی خوابانیدن، کیف­های کلش از خاک خارج و پس از اندازه­گیری وزن بقایای گیاهی باقی­مانده در آن­ها میزان کربن آلی نیتروژن کل بقایا اندازه­گیری شد. نتایج نشان داد که بیشترین مقدار هدر رفت کربن و نیتروژن آلی چهار ماه پس از خوابانیدن، زمانی­که بقایای گیاهی گندم با اندازه 2/0 تا 5/0 سانتی­متری در عمق 30 سانتی­متری خاک جایگذاری شدند اتفاق افتاد. در مقابل کمترین مقدار هدر رفت کربن و نیتروژن آلی یک ماه پس از خوابانیدن، زمانی­که بقایای گیاهی گندم با اندازه 5 تا 10 سانتی­متری در عمق پنج سانتی­متری خاک جایگذاری شدند صورت پذیرفت. در این آزمایش 73/49 تا 07/54 درصد از کربن آلی و 48/34 تا 78/39 درصد از نیتروژن آلی بقایای گندم در یک دوره چهار ماهه وقتی بقایای گیاهی گندم به­ترتیب در عمق 5 و 30 سانتی­متری خاک جایگذاری شدند تلف گردید. از نتایج چنین استنباط می­شود زمانی­که کمبود رطوبت خاک عامل محدود­کننده برای تجزیه بقایای گیاهی است، افزایش عمق جایگذاری بقایا با قرار دادن بقایا در لایه مرطوب خاک باعث افزایش سرعت معدنی شدن کربن و نیتروژن آلی می­شود. همچنین خرد کردن بقایای گیاهی با افزایش سطح ویژه و سطح تماس بقایا با خاک، باعث افزایش سرعت تجزیه بقایا می­شود.

کلیدواژه‌ها


عنوان مقاله [English]

Effects of Size and Placement Depth of Plant Residues on Organic Carbon and Nitrogen Dynamics

نویسندگان [English]

  • Vahideh Safi 1
  • Ahmad Golchin 1
  • saeid shafiei 2
1 University of Zanjan
2 university of Jiroft
چکیده [English]

Introduction
Prediction of mineralization rate of organic carbon and nitrogen amounts of plant residues is important due to plant nutrient management, carbon dioxide production and environmental issues. Plant residues characteristics such as total nitrogen content (N), carbon: nitrogen (C/N), lignin content and particle size, Soil characteristics (texture, structure, pH and the microbial population) and Climate (temperature and moisture) are the most important factors affecting plant residues decomposition. Decomposition process of plant residues is influenced by substrate quality, decomposer community and environmental factors. Within a given climatic region, litter chemistry is the main determinant of litter decomposition. Litter decay and nutrient release are controlled by the litter quality, including the nitrogen (N) concentration of the litter, the carbon to nitrogen (C/N) ratio, as well as other chemical properties.
Materials and methods
To investigate the effects of size and placement depth of plant residues on organic carbon and nitrogen dynamics, a split – split plot layout based on a randomized complete block design and three replications was conducted using litter bag method. The factors were depths of incubation periods of plant residues (1, 2, 3 and 4 months), placement of plant residues (5, 15, 30 and 45 cm) and sizes of plant residues (0.2 - 0.5, 1 - 2 and 5 - 10 cm) which were located in main, sub and sub-sub plots respectively. At the end of the incubation period, the litter bags were pulled out of the pots; after the weights of the remaining plant residues in the bags were measured, the residue organic carbon was measured via the dry combustion method at 450°C for 5 h and the total nitrogen via the kjeldahl method. We analyzed the collected data during desert-lab studies by SAS/STAT software release 9.1. Statistical differences among size and placement depth of plant residues and time duration were determined using a generalized linear model (Proc GLM), P ≤ 0.05 and LSMEANS, which allows mean comparisons even when data points are missing.
Results and discussion
Results of data variance decomposition indicated that size and placement depth of plant residues had a significant effect on carbon and nitrogen loss at the probable level of 1℅ .The highest organic carbon and nitrogen loss were measured after four month of incubation and when the size and the depth of placement of plant residues were 0.2 - 0.5 and 30 cm, respectively. The lowest organic carbon and nitrogen loss were also obtained after the first month of incubation and when the size and the depth of placement of plant residues were 5 - 10 and 5 cm, respectively. After four months of incubation 49.73 and 54.07% of organic carbon and 34.48 and 39.78 of organic nitrogen of plant residues mineralized when the depths of placement of plant residues were 5 and 30cm respectively. Aridity, soil hilling and availability to nutrients are determining factors of the carbon cycle in the decomposition process. Conceptually and analytically advanced models from diverse studies suggest three factors affecting decomposition in  arid ecosystems: quality and quantity of the organic matter under decomposition, the physical environment (including temperature, precipitation and soil type) and the nature and entity of the decomposing organs in the soil.
Conclusion
 From the results it was concluded that when the soil moisture level is a limiting factor for plant residue mineralization, increasing the depth of placement of plant residues enhances the rate of mineralization of organic carbon by providing sufficient moisture for plant residues decomposition. The results also showed that reducing plant residues particle size with increases the surface area and plant residues contact with the soil, enhances the rate of decomposition of plant residues.

کلیدواژه‌ها [English]

  • Plant residues size
  • Plant residues depth of Placement
  • Organic carbon dynamics
Abiven, S., and Recous, S. 2007. Mineralisation of crop residues on the soil surface or incorporated in the soil under controlled conditions. Biology and Fertility of Soils 43(6): 849-852.
Berg, B., and MacClaughtery, C. 2008. Plant Litter: Decomposition, Humus Formation, Carbon Sequestration. Springer-Verlag. New York.
AOAC: Official Methods of analysis, Method 978.04.
Angers, D.A., and Recous, S. 1997. Decomposition of wheat straw and rye residues as affected by particle size. Plant and Soil 189(2): 197-203.
Austin, A.T., and Vivanco, L. 2006. Plant litter decomposition in a semi-arid ecosystem controlled by photodegradation. Nature 442: 555- 558.
Berg, B., Johansson, M.B., and Meentemeyer, V. 2000. Litter decomposition in a transect of Norway spruce forests: substrate quality and climate control. Canadian Journal of Forest Research 30(7): 1136-1147.
Berg, B., and McClaugherty, C. 2003. Plant Litter: Decomposition, Humus Formation and Carbon Sequestration. Springer: Berlin, Gemany 311 pp.
Blume, H.P., Brümmer, G.W., Fleige, H., Horn, R., Kandeler, A.E., Kögel-Knabner, I., Kretzschmar, R., Stahr, K., and Wilke, B.M. 2015. Scheffer/Schachtschabel soil science. Springer. Germany p. 420.
Fog, K. 1988. The effect of added nitrogen on the rate of decomposition of organic matter. Biological Reviews 63(3): 433-462.
Gee, G.W., and Bauder, J.W. 1986. Particle-size analysis, p. 383-411. In: Klute, A. (Ed), Methods of soil analysis, part 1: Physical and mineralogical methods. Soil Science Society of America. Madison, Wisconsin, USA.
Giacomini, S., Recous, S., Mary, B., and Aita, C. 2007. Simulating the effects of N availability, straw particle size and location in soil on C and N mineralization. Plant and Soil 301(1-2): 289-301.
Guntinas, M., Leiros, M., Trasar, C., and Gil, F. 2012. Effects of moisture and temperature on net soil nitrogen mineralization: a laboratory study. European Journal of Soil Biology 48: 73-80.
Hesse, P.R. 1971. A Text Book of Soil Chemical Analysis. John Murray. London. United Kingdom p. 520.
Iqbal, A., Garnier, P., Lashermes, G., and Recous, S. 2014. A new equation to simulate the contact between soil and maize residues of different sizes during their decomposition. Biology and Fertility of Soils 50(4): 645-655.
Kisselle, K.W., Garrett, C.J., Fu, S., Hendrix, P.F., Crossley Jr, D.A., Coleman, D.C., and Potter, R.L. 2001. Budgets for root-derived C and litter-derived C: comparison between conventional tillage and no tillage soils. Soil Biology and Biochemistry 33(7-8): 1067-1075.
Li, L.J., Han, X.Z., You, M.Y., Yuan, Y.R., Ding, X.L., and Qiao, Y.F. 2013. Carbon and nitrogen mineralization patterns of two contrasting crop residues in a Mollisol: Effects of residue type and placement in soils. European Journal of Soil Biology 54: 1-6
Murungu, F., Chiduza, C., Muchaonyerwa, P., and Mnkeni, P. 2011. Decomposition, nitrogen and phosphorus mineralization from winter-grown cover crop residues and suitability for a smallholder farming system in South Africa. Nutrient Cycling in Agroecosystems 89: 115-123.
Nelson, D.W., and Sommer, L. E. 1982. Total carbon, organic carbon, and organic matter, p. 595- 624. In: A.L. Page (Eds.). Methods of soil analysis. Part 2. Chemical and Microbiological Properties. American Society of Agronomy. Madison, W.I.
Olson, J.S. 1963. Energy storage and balance of producers and decomposition in ecological systems. Ecology Society of America 44(2): 322- 331
Oades, J.M. 1993. The role of biology on the formation, stabilization and degradation of soil structure. Geoderma 56: 377-400.
Puget, P., a nd Drinkwater, L. 2001. Short-term dynamics of root-and shoot-derived carbon from a leguminous green manure. Soil Science Society of America Journal 65(3): 771-779.
Rhoades, J.D. 1996. Salinity: Electerical conductivity and total dissolved soils, p. 417-435. In: Sparks, D.L. (Ed.), Methods of Soil Analysis. Part 3, Chemical methods. Soil Science Society of America. Madison, WI.
Rovira, P., and Vallejo, V. 1997. Organic carbon and nitrogen mineralization under Mediterranean climatic conditions: the effects of incubation depth. Soil Biology and Biochemistry 29(9): 1509-1520.
Sims, J.L., and Frederick, L. R. 1970. Nitrogen immobilization and decomposition of corn residue in soil and sand as affected by residue particle size. European Journal of Soil Science 109(6): 355-361.
Shafiei, S., Golchin, A., and Delavar, M.A. 2016. Effect of residue nitrogen concentration and time duration on carbon mineralization rate of alfalfa residues in regions with different climatic conditions. Journal of Agroecology 8(3): 397-416. (In Persian with English Summary)
Song, C., Liu, D., Yang, G., Song, Y., and Mao, R. 2011. Effect of nitrogen addition on decomposition of Calamagrostis angustifolia litters from freshwater marshes of Northeast China. Ecological Engineering 37(10): 1578-1582.
Tate, III. R. L. 2000; Soil Microbiology. 2nd Edition. John Wiley and Sons. NY.
Tarafdar, J.C., Meena, S.C., and Kathju, S. 2001. Influence of straw size on activity and biomass of soil microorganisms during decomposition. European Journal of Soil Biology 37(3): 157-160.
Thomas, G.W. 1996. Soil pH soil acidity, P 475-490. In: Sparks D.L. (Ed.), Methods of soil analysis. Part 3, Chemical methods. ASA, Madison, WI.
Zibilske, L., and Bradford, J. 2007. Oxygen effects on carbon, polyphenols, and nitrogen mineralization potential in soil. Soil Science Society of America Journal 71(1): 133-139