Karunaichamy, K.

Paliwal, Kailash

English

University of Kentucky

University of Kentucky UKnowledge International Grassland Congress Proceedings 21st International Grassland Congress / 8th International Rangeland Congress Nutrient Dynamics in a Semi‐Arid Grazing Land of Southern India K. Karunaichamy Rubber Research Institute of India, India Kailash Paliwal Madurai Kamaraj University, India Follow this and additional works at: https://uknowledge.uky.edu/igc  Part of the Plant Sciences Commons, and the Soil Science Commons This document is available at https://uknowledge.uky.edu/igc/21/2-1/20 The 21st International Grassland Congress / 8th International Rangeland Congress took place in Hohhot, China from June 29 through July 5, 2008. Proceedings edited by Organizing Committee of 2008 IGC/IRC Conference Published by Guangdong People's Publishing House This Event is brought to you for free and open access by the Plant and Soil Sciences at UKnowledge. It has been accepted for inclusion in International Grassland Congress Proceedings by an authorized administrator of UKnowledge. For more information, please contact UKnowledge@lsv.uky.edu. 　 Multifunctional Grasslands in a Changing World 　 Volume Ⅰ 　 瞯 ]315　 瞯Grasslands/Rangelands Resources and Ecology ——— Soil Quality and Plant NutritionNutrient dynamics in a semi‐arid grazing land of southern IndiaK . K arunaichamy 1 and K . Paliw al21 Rubber Research Institute o f India , Kottayam 686 009 , India . E‐mail : karunai＠ rubberboard .org .in .2 Department o f Plant Sciences , Madurai K amaraj University , Madurai 625 021 , IndiaKey words : annual uptake , grazed , live shoots , nutrient dynamics , semi‐aridIntroduction Cycling and distribution of minerals in various compartments of the ecosystem is most important aspects ecosystemstudy . The semi‐arid grazing land ecosystem at Madurai developed under short evolutionary grazing histories and low moistureregimes , in which grazing pressure has dramatic effects on plant community and biomass ( Karunaichamy , １９９２) . The objectiveof this experiment was to study the distribution of N , P and K in the vegetation components and to estimate the annual nutrientbudget in grazed and ungrazed lands dominated by Chrysopogon f ulvus ( Spreng ) Chiov .Materials and methods The study area is located in the southern part of Tamil Nadu (９°５８′N ; ７８°１０′E) at an altitude of １００mabove mean sea level . Average monthly temperature ranges between ３５ .３ ℃ and ２５ .３ ℃ . The mean annual rainfall was ５７１ mmduring the two‐year study . Twenty quadrants of ５０ × ５０ cm were sampled randomly in grazed and ungrazed areas at monthlyintervals . Litter was collected carefully from each plot . The root phytomass was evaluated by excavating soil cores of ２５ × ２５ ×３０ cm . Soil samples (３０ cm depth) were also taken at the same harvested plot for determination of soil nutrients . Total N andP in plant components and soil were digested and analyzed colorimetrically by an autoanalyzer . Potassium was estimated usingan atomic absorption spectrophotometer . The transfer of nutrients between various compartments and the release of nutrientsthrough root and litter disappearance were calculated following balance sheet approach ( Singh and Yadava , １９７４) .Results The live shoot component showed higher content of N , P and K in the grazed plot ( Table １ ) . Live shoots containshigher nutrient content than other components . The trends of soil nutrient concentrations were in the following order K ＞ N ＞P in both grazed and ungrazed areas . The maximum storage of nutrients was in lives shoots and root components . Content of Nand K (mg /m２ ) in live shoots showed a significant positive relationship with a linear combination of rainfall , air temperatureand soil moisture in both grazed and ungrazed plot .Table 1 Nutrient ( ％ ) in the vegetation components ( ± S .E ; n ＝ ５ ) . V alues in the parenthesis are ungrazed p lot .Components N P KLive shoots １ G.８５ ± ０ .０４(１ .６７ ± ０ .０４ ) ０ 亮.０８ ± ０ .０１(０ .０５ ± ０ .００) ０ J.７５ ± ０ .０６(０ .９４ ± ０ .０９)Dead shoots １ G.６０ ± ０ .０７(１ .４９ ± ０ .０６ ) ０ 亮.０７ ± ０ .０１(０ .０４ ± ０ .０１) ０ J.４９ ± ０ .０４(０ .５９ ± ０ .０９)Litter １ G.５７ ± ０ .０８(１ .５２ ± ０ .０８ ) ０ 亮.０３ ± ０ .００(０ .０４ ± ０ .０１) ０ J.５０ ± ０ .０９(０ .４８ ± ０ .０８)Roots １ G.６４ ± ０ .０７(１ .３６ ± ０ .０８ ) ０ 亮.０５ ± ０ .０１(０ .０４ ± ０ .００) ０ J.５９ ± ０ .０５(０ .５９ ± ０ .０７)Total uptake of nutrients in plant components was higher in the ungrazed plot than grazed plot ( Table ２) . In the grazed plot , ofthe total ecosystem nutrients , less than ４％ of N and １％ of P & K were channeled through biological cycling . About ９５％ ofthe nutrients remain in the root debris , organic matter and soil fractions . In the grazed plot , annual release of nutrients in litterand roots to soil was lower than the ungrazed plot .Table 2 Net up take , release and retention o f nutrient (kg / ha/ year) V alues in the parenthesis are ungrazed p lots .Nutrients Soil Uptake Retention ReleaseN ５１４９(５２８６) １８５ (２５６) ９１ 眄.３(７１ .７) ９３ 腚.７(１８４ .３)P ９０５( ９９１) ７ 览.２(７ .６ ) ４ 靠.３(２ .６ ) ２ 浇.９(５ .０)K ５８２８(７５６６) ７０ 铑.９(１２４ .３) ３７ 眄.５(４８ .３) ３３ 腚.４(７６ .０)Conclusions Cycling of mineral elements in a semi‐arid grazing land was regulated by both live shoot and root compartments andfaster recycling through root decomposition . Heavy grazing affects productivity and gives way to unpalatable species forinvasion ( Barleria bux i f olia Linn .) .The present study clearly indicates that heavy grazing not only degrades the nutrienteconomy of the system but also slows nutrient cycling within the plant biomass .ReferencesKarunaichamy , K . , １９９２ . Biomass dynamics and nutrient composition in grazing land ecosystem of Western Ghats region ofTamil Nadu . Ph .D thesis , Madurai Kamaraj University , Madurai , India .Singh , J .S . , Yadava , P .S . , １９７４ . Seasonal variation in composition , plant biomass and net primary productivity of a tropicalgrassland at Kruukshetra . Ecological Monographs ４４ , ３５１‐３７６ .

Nutrient Dynamics in a Semi‐Arid Grazing Land of Southern India

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Nutrient Dynamics in a Semi‐Arid Grazing Land of Southern India

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