INDEKS PRODUKTIVITAS TANAH. PRODUCTIVITY INDEX RATING OF SOILS Sumber: Productivity index rating of some soils in the Tolon/Kumbungu district of the Northern.

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1 INDEKS PRODUKTIVITAS TANAH

2 PRODUCTIVITY INDEX RATING OF SOILS Sumber: Productivity index rating of some soils in the Tolon/Kumbungu district of the Northern region of Ghana. Imoro Abukari Ziblim, Daniel Okai-Anti and E. Augustine Asmah. Journal of Soil Science and Environmental Management Vol. 3(6), pp. 154-163, 2012 Indeks Produktivitas (PI) dapat digunakan untuk menilai (rating) tanah-tanah menurut kesesuaiannya untuk produksi tanaman. Beberapa serie tanah dinilai (diuji) potensi produksinya, yaitu Serie Nyankpala (NS), Serie Changnayili (CS) dan Serie Kpelesawgu (KS), dievaluasi kesesuaiannya saat sekarang dan di masa mendatang, serta untuk memperkirakan tindakan apa saja untuk memperbaiki produktivitasnya. Tanaman uji dapat digunakan jagung, kedelai dan kac tanah. Soil samples were taken from 0 to 20 cm and 20 to 40 cm depths, and soil and crop data were rated and scaled using 100% as the optimum and the Productivity index (PI) ratings for the series were computed.

3 PRODUCTIVITY INDEX RATING OF SOILS Sumber: Productivity index rating of some soils in the Tolon/Kumbungu district of the Northern region of Ghana. Imoro Abukari Ziblim, Daniel Okai-Anti and E. Augustine Asmah. Journal of Soil Science and Environmental Management Vol. 3(6), pp. 154-163, 2012 Seri tanah KS mempunyai nilai PI lebih tinggi, sedengkan seri tanah NS nenounyai nilai PI paling rendah. This might mean that KS has higher productivity potential than both CS and NS. All three soil series showed low current suitability for crop production, however, given prudent soil management practices, the soils would be potentially suitable for crop production. Direkomendasikan pengelolaan tanah dilakukan untuk memperbaiki pH tanah dan memasukkan bahan organik untuk meningkatkan produktivitasnya.

4 PRODUCTIVITY INDEX RATING OF SOILS Sumber: Productivity index rating of some soils in the Tolon/Kumbungu district of the Northern region of Ghana. Imoro Abukari Ziblim, Daniel Okai-Anti and E. Augustine Asmah. Journal of Soil Science and Environmental Management Vol. 3(6), pp. 154-163, 2012 Produktivitas tanah merupakan kemampuan tanah menghasilkan suatu jenis tanaman pada kondisi pengelolaan tertentu. Produktivitas menekankan kapasitas tanah untuk memproduksi tanaman dan harus dinyatakan dalam bentuk “hasil tanaman” (Brady and Weil, 1999). To quantify soil productivity, there have been several attempts at devising systems that provide a productivity index, or rating, by means of numerical or parametric methods or approach (Delgado and Lopez, 1998). Model Indeks Produktivitas (PI) merupakan ukuran produktivitas tanah. 1.Brady NC, Weil RR (1999). The nature and properties of soil. 12th ed. Prentice Hall, New Jersey, USA. p. 852. 2.Delgado F, Lopez R (1998). Evaluation of soil degradation impact on the productivity of Venezuelan soils. Adv. GeoEcol., 31:133-142.

5 PRODUCTIVITY INDEX RATING OF SOILS Sumber: Productivity index rating of some soils in the Tolon/Kumbungu district of the Northern region of Ghana. Imoro Abukari Ziblim, Daniel Okai-Anti and E. Augustine Asmah. Journal of Soil Science and Environmental Management Vol. 3(6), pp. 154-163, 2012 Productivity index is an algorithm based on the assumption that crop yield is a function of root-growth, including rooting depth, which is controlled by the soil environment (Lindstrom et al., 1992). 1.Lindstrom MJ, Schumacher TF, Jones AJ, Gantzer CJ (1992). Productivity index model comparison for selected soils in North Central United States. J. Soil and Water Conserv., 47(6): 491-494. Indeks Produktivitas Tanah Pertumbuhan akar Kedalaman perakaran Lingkungan Tanah

6 PRODUCTIVITY INDEX RATING OF SOILS Sumber: Productivity index rating of some soils in the Tolon/Kumbungu district of the Northern region of Ghana. Imoro Abukari Ziblim, Daniel Okai-Anti and E. Augustine Asmah. Journal of Soil Science and Environmental Management Vol. 3(6), pp. 154-163, 2012 Indeks productivitas didasarkan pada sifat-sifat tanah yg mudah diukur untuk memprediksi efek lingkungan tanah terhadap pertumbuhan tanaman. Penilaian IP biasanya terdiri atas persamaan matematis yg diturunkan secara empirik, untuk menghubungkan produktivitas dengan nilai-nilai parametrik dari sifat-sifat tanah. Setiap sifat tanah mempunyai kiisaran nilai numerik tertentu, dan kemudian nilai-nilai ini dimasukkan ke dalam persamaan matematik untuk menghitung IP (Ilaco, 1981). 1.Ilaco BV (1981). Agricultural compendium for rural development in the tropics and sub-tropics. Elsevier, Amsterdam. p. 739

7 PRODUCTIVITY INDEX RATING OF SOILS Sumber: Productivity index rating of some soils in the Tolon/Kumbungu district of the Northern region of Ghana. Imoro Abukari Ziblim, Daniel Okai-Anti and E. Augustine Asmah. Journal of Soil Science and Environmental Management Vol. 3(6), pp. 154-163, 2012 Efek kombinasi dari berbagai faktor (parameter) lebih bersifat multiplikatif (perkalian) dan bukan adetif (penjumlahan). IP mempunyai keuntungan karena tidak terlalu terpengaruh oleh perubahan teknologi, dibandingkan dnegan model produktivitas yang berdasarkan hasil tanaman. Akan tetapi metode evaluasi IP ini lebih sesuai untuk aplikasi lokal, dan kurang sesuai untuk maplikasi universal (Russell, 1988). 1.Russell EW (1988). Soil conditions and plant growth. Wild, A. (ed.), 11th edition. Longman Group UK Ltd. Reino Unido. ISBN 0-582-44677-5. pp. 357- 991.

8 PRODUCTIVITY INDEX RATING OF SOILS Sumber: Productivity index rating of some soils in the Tolon/Kumbungu district of the Northern region of Ghana. Imoro Abukari Ziblim, Daniel Okai-Anti and E. Augustine Asmah. Journal of Soil Science and Environmental Management Vol. 3(6), pp. 154-163, 2012 Metode-metode untuk evaluasi Produktivitas Tanah Ada berbagai macam teknik dan filosofi evaluasi produktivitas tanah. Beberapa metode lebih berkonsentrasi pada derajat kesesuaian sifat- sifat tanah, dan metode lainnya lebih mneekankan pada faktor pembatas tanah untuk penggunaan tertentu. Beberapa metode mengelompokkan tanah menjadi beberapa (order, class dan tipe tanah), sedangkan metode lainnya menggunakan pendekatan hierarkhis. Other systems have one category, and these are frequently parametric. In these later systems, mathematical formulae are applied such that the final result is expressed in numerical terms. These can be additive or with a multiplicative scheme, the latter offering better results.

9 PRODUCTIVITY INDEX RATING OF SOILS Sumber: Productivity index rating of some soils in the Tolon/Kumbungu district of the Northern region of Ghana. Imoro Abukari Ziblim, Daniel Okai-Anti and E. Augustine Asmah. Journal of Soil Science and Environmental Management Vol. 3(6), pp. 154-163, 2012 Metode-metode parametrik yang dikembangkan oleh McRae dan Burnham (1981), dianggap sederhana, objective, quantitatif, dapat dipercaya, mudah dipahami dan diaplikasikan, dan mudah dimodifikasi dan disessuaikan dengan penggunaan baru. Pierce et al. (1983) menggunakan model indeks produktivitas untuk memprediksi produksi tanaman berdasarkan data-data tentang WHC (water-holding capacity) tanah, pH, dan resistensi thd pertumbuhan akar. Wilson et al. (1991) menggunakan model matematik untuk estimasi hasil tanaman berdasarkan data BOT dan kandungan CaCO3 dalam tanah. 1.McRae SG, Burnham CP (1981). Land evaluation, Monogr. Soil Survey. Clarendon Press. p. 239. 2.Pierce FJ, Larson WE, Dowdy RH, Graham WAP (1983). Productivity of soils: Assessing long-term changes due to erosion. J. Soil Water Conserv., pp. 38, 39-44.

10 PRODUCTIVITY INDEX RATING OF SOILS Sumber: Productivity index rating of some soils in the Tolon/Kumbungu district of the Northern region of Ghana. Imoro Abukari Ziblim, Daniel Okai-Anti and E. Augustine Asmah. Journal of Soil Science and Environmental Management Vol. 3(6), pp. 154-163, 2012 Biasanya PI dihitung dengan menggunakan rumus multifaksional berikut (Delgado, 1998). dimana : PI = Productivity index; Ai = Kondisi yg mengendalikan relasi lengas tanah horison ke-i. Bi = Kondisi yg menentukan resistensi mekanis (impedances) terhadap eksplorasi akar tanaman dalam horison ke-i. Ci = Kondisi yg mengendalikan kesuburan potensial horison ke-i. Ki = Kepentingan relatif horison ke-i. dan juga kedalaman tanah. 1.Delgado F, Lopez R (1998). Evaluation of soil degradation impact on the productivity of Venezuelan soils. Adv. GeoEcol., 31:133-142.

11 PRODUCTIVITY INDEX RATING OF SOILS Sumber: Productivity index rating of some soils in the Tolon/Kumbungu district of the Northern region of Ghana. Imoro Abukari Ziblim, Daniel Okai-Anti and E. Augustine Asmah. Journal of Soil Science and Environmental Management Vol. 3(6), pp. 154-163, 2012 The soil stores the water and air used by plants to sustain life. The amount of soil water that can be used by the plant varies, due to the characteristics of the soil, for example, soil texture of the plant, root distribution and depth (Tolk, 2003). These models use physical and chemical soil parameters such as bulk density, soil moisture content, and soil texture, depth to iron pan/concretions, effective rooting depth, Soil Organic Matter (SOM), Effective Cation Exchange Capacity (ECEC) and pH to quantify the productivity of soils. Model-model ini belum mempertimbangkan semua faktor fisik dan lingkungan yg mempengaruhi Produktivitas Tanah. 1.Tolk JA (2003). Plant Available Soil Water. United States Department of Agriculture (USDA), Bushland, Texas, U. S. A. Marcel Dekker pp. 669-672.

12 PRODUCTIVITY INDEX RATING OF SOILS Sumber: Productivity index rating of some soils in the Tolon/Kumbungu district of the Northern region of Ghana. Imoro Abukari Ziblim, Daniel Okai-Anti and E. Augustine Asmah. Journal of Soil Science and Environmental Management Vol. 3(6), pp. 154-163, 2012 Model yang dipakai Model Storie (1978) dimodifikasi sedikit. Parameter terukur berikut ini dipilih dan ditentukan: PI = H × T x B × D × E × O × A × S, Dimana: H = kandungan lengas tanah; T = tekstur tanah; B = bobot isi; D = kedalaman cadas besi; E = kedalaman efektif perakaran; O = kandungan bahan organik; A = Kapasitas tukar kation (CEC); S = reaksi tanah (pH). Pemilihan parameter tersebut berdasarkan pada kondisi lingkungan tanah di lokasi penelitian. 1.Storie RE (1978). Storie index rating (revised). Special Publication 3203, Division of Agricultural Sciences, University of California, Berkley, California.

13 PRODUCTIVITY INDEX RATING OF SOILS Sumber: Productivity index rating of some soils in the Tolon/Kumbungu district of the Northern region of Ghana. Imoro Abukari Ziblim, Daniel Okai-Anti and E. Augustine Asmah. Journal of Soil Science and Environmental Management Vol. 3(6), pp. 154-163, 2012 Jenis Tanaman yang Diuji Untuk evaluasi produktivitas tanah (hasil tanaman) pada kondisi aktual, dapat digunakan empat jenis tanaman; yaitu jagung, kedelai, kac. Tunggak dan kac. tanah. Tanaman ditanam secara monokultur pada setiap serie tanah dan diamati pola pertumbuhannya. Parameter pertumbuhan yg diamati: tinggi tanaman, jumlah daun/tanaman, lebar daun, dan panjang daun. The yield was then determined after the crops were harvested. Measurements started three weeks after germination and continued every two weeks till maturity/harvesting. Setelah panen tanaman, 1000 biji setiap jenis tanaman ditimbang untuk menentukan hasil-tanaman.

14 PRODUCTIVITY INDEX RATING OF SOILS Sumber: Productivity index rating of some soils in the Tolon/Kumbungu district of the Northern region of Ghana. Imoro Abukari Ziblim, Daniel Okai-Anti and E. Augustine Asmah. Journal of Soil Science and Environmental Management Vol. 3(6), pp. 154-163, 2012 Efek Lengas Tanah thd Karakteristik Tanah Hasil penelitian menunjukkan bahwa kandungan lengas tanah beragam dnegan kedalaman tanah. Lapisan tanah pd kedalaman 20 - 40 cm mempunyai kandungan lengas lebih tinggi dibandingkan dengan kedalaman 0 - 20 cm. Rawls et al. (2003) melaporkan bahwa pada tanah-tanah kasar, peningkatan C-organik dapat meningkatkan retensi air. Dalam tanah- tanah yg kaya liat (>19% liat), daya retensi airnya meningkat dnegan meningkatnya kandungan liat. Rendahnya kandungan lengas tanah pd kedalaman 0 - 20 cm mungkin disebabkan oleh rendahnya kandungan liat dan BOT. 1.Rawls WJ, Pachepsky YA, Ritchie JC, Sobecki TM, Bloodworth H (2003). Effect of soil organic carbon on soil water retention. Geoderma, 116: 61– 76.

15 PRODUCTIVITY INDEX RATING OF SOILS Sumber: Productivity index rating of some soils in the Tolon/Kumbungu district of the Northern region of Ghana. Imoro Abukari Ziblim, Daniel Okai-Anti and E. Augustine Asmah. Journal of Soil Science and Environmental Management Vol. 3(6), pp. 154-163, 2012 Tanah CS dan KS pada kedalaman 20-40 cm mempunyai kandungan lengas lebih tinggi, hal ini ada hubungannya dengan tingginya kandungan liat dan BOT. Hudson (1994) menemukan bahwa kemampuan tanah menyimpan air-tersedia dipengaruhi oleh kandungan BOT nya. 1.Hudson B (1994). Soil Organic Matter and Available Water Capacity. J. Soil and Water Conserv., pp. 189-193.

16 PRODUCTIVITY INDEX RATING OF SOILS Sumber: Productivity index rating of some soils in the Tolon/Kumbungu district of the Northern region of Ghana. Imoro Abukari Ziblim, Daniel Okai-Anti and E. Augustine Asmah. Journal of Soil Science and Environmental Management Vol. 3(6), pp. 154-163, 2012 Kedalaman tanah berpengaruh terhadap kemampuan tanah menyimpan lengas-tanah. Menurut Webster and Wilson (1980), tanah- tanah yang dalam (tebal) menyimpan lebih banyak air dibandingkan dengan tanah-tanah yang dangkal (tipis). 1.Webster CC, Wilson PN (1980). Agriculture in the tropics. Longman, London, UK. p. 640.

17 PRODUCTIVITY INDEX RATING OF SOILS Sumber: Productivity index rating of some soils in the Tolon/Kumbungu district of the Northern region of Ghana. Imoro Abukari Ziblim, Daniel Okai-Anti and E. Augustine Asmah. Journal of Soil Science and Environmental Management Vol. 3(6), pp. 154-163, 2012 Tabel 2. Some physical properties of Nyankpala, Changnayili and Kpelesawgu series at 0 to 20 and 20 to 40 cm sampling depths.

18 PRODUCTIVITY INDEX RATING OF SOILS Sumber: Productivity index rating of some soils in the Tolon/Kumbungu district of the Northern region of Ghana. Imoro Abukari Ziblim, Daniel Okai-Anti and E. Augustine Asmah. Journal of Soil Science and Environmental Management Vol. 3(6), pp. 154-163, 2012 Tekstur dan Karakteristik Tanah Tanah-tanah yang diteliti ternyata teksturnya lempung berpasir pada kedalaman 0 - 20 cm dan 20 - 40 cm. Persen liat dan persen debu menurun dnegan kedalaman, sedangkan persen pasir meningkat. Persen pasir pada dua lapisan tanah tersebut ternyata “tinggi”, diikuti oleh persen debu dan kemudian persen liat paling rendah. (Table 2).

19 PRODUCTIVITY INDEX RATING OF SOILS Sumber: Productivity index rating of some soils in the Tolon/Kumbungu district of the Northern region of Ghana. Imoro Abukari Ziblim, Daniel Okai-Anti and E. Augustine Asmah. Journal of Soil Science and Environmental Management Vol. 3(6), pp. 154-163, 2012 Tanah-tanah berpasir yang diteliti diduga mempunyai kesuburan yang terbatas dan tidak mampu menahan banyak air tersedia dan hara tersedia. Menurut Bruand et al. (2007), tanah-tanah berpasir berbeda dnegan tanah lainnya, agregasinya mudah digemburkan dnegan pengolahan tanah, sehingga dihasilkan porositas yng lebih besar tetapi stabilitasnya sangat lemah. Hal ini mengakibatkan penurunan sifat-sifat retensi air. 1.Bruand A, Hartmann C, Lesturgez G (2007). Physical properties of tropical sandy soils: A large range of behaviours. FAO Corporate Document Repository, Physical properties of tropical sandy soils. http://www.fao.org/docrep/010/ag125e/ag125e00.htm Retrieved: 14/02/2012.

20 PRODUCTIVITY INDEX RATING OF SOILS Sumber: Productivity index rating of some soils in the Tolon/Kumbungu district of the Northern region of Ghana. Imoro Abukari Ziblim, Daniel Okai-Anti and E. Augustine Asmah. Journal of Soil Science and Environmental Management Vol. 3(6), pp. 154-163, 2012 Temuan Tsimba et al. (1999) bahwa, bobot isi tanah meningkat dnegan kedalaman tanah, mungkin karena rendahnya kandungan BOT, kurangnya agregasi dan terbatasnya penetrasi tanah, serta adanya tekanan dari lapisan tanah di atasnya. 1.Tsimba R, Hussein J, Ndlovu LR (1999). Relationships between depth of tillage and soil physical characteristics of sites farmed by smallholders in Mutoko and Chinyika in Zimbabwe. Published in: Kaumbutho PG, Simalenga TE (1999). Conservation tillage with animal traction. A resource book of the Animal Traction Network for Eastern and Southern Africa (ATNESA). Harare. Zimbabwe. p. 173 http://www.atnesa.org/contil/contil-tsimba-depth- ZW.pdf Retrieved: 13/02/2012.

21 PRODUCTIVITY INDEX RATING OF SOILS Bobot Isi dan Karakteristik Tanah The bulk density range of 1.53 to 1.59 g cm-3 in the 0 to 20 cm and 1.60 to 1.67 g cm-3 in the 20 to 40 cm depth are both below the critical value of 2.1 g cm-3, beyond which plant root growth is severely limited. The bulk density values presented in Table 2 are within the limits given by Bowen (1981) and Kar et al. (1976), beyond which root growth is impeded and crop production is reduced. Umumnya nilai-nilai BI yang tinggi pd kedalaman 20 - 40 cm mungkin ada hubungannya dengan tekstur dan pengolahan tanah yg kontinyu dan dibarengi oleh aktivitas “grazing animals”. Rendahnya kandungan BOT menyebabkan nilai BI yang tinggi. 1.Bowen HD (1981). Alleviating mechanical impedance. In: Arkin G.F. and Taylor, H.M. (eds.). Modifying the root environment to reduce crop stress, ASAE, pp. 21-57. 2.Kar S, Varade SB, Subramanyan TK, Ghildyal BP (1976). Soil physical conditions affecting rice root growth: bulk density and submerged soil temperature regime effects, Agro. J., 68:23-26.

22 PRODUCTIVITY INDEX RATING OF SOILS Kedalaman Cadas Besi Adanya cadas-besi dalam zone perakaran dapat menghalangi pertumbuhan akar tanaman dan hal ini mempengaruhi potensial produktivitas tanah. The mean depths of 39.0, 32.6 and 61.2 cm to iron concretions of NS, CS and KS soils respectively, show the development of iron pan towards the soil surface especially, the NS and CS soils and this can have strong resistance to root penetration and development. Adanya cadas-besi pd lapisan yg dangkal mungkin karena pelapukan bahan induk tanah dan pengolahan tanah yg kontinyus pada kedalaman yang sama (Waddington, 1991; Unger and Kasper, 1994). 1.Unger PW, Kasper TC (1994). Soil compaction and root growth: A review. Agro. J., 86: 759-766. 2.Waddington SR (1991). Agronomic problems related to tillage on small holder cereal production and some research opportunities. Proceedings of a Workshop held at the Institute of Agricultural Engineering on tillage. Past and future. Harare 14 and 15 November 1989, pp. 46-57.

23 PRODUCTIVITY INDEX RATING OF SOILS Sumber: Productivity index rating of some soils in the Tolon/Kumbungu district of the Northern region of Ghana. Imoro Abukari Ziblim, Daniel Okai-Anti and E. Augustine Asmah. Journal of Soil Science and Environmental Management Vol. 3(6), pp. 154-163, 2012 HUBUNGAN KEDALAMAN PERAKARAN DG SIFAT-SIFAT TANAH The mean rooting depths of 51.0, 47.6 and 55.2 cm for NS, CS and KS soils respectively, showed that the soils are shallow (Table 2). KS soils appeared to be relatively deeper. Solum tanah yang dangkal mungkin ada hubungannya dnegan sifat bahan induk tanah dan sejarah budidaya tanaman di lokasi. Erosi tanah dapat menjadi faktor penting, karena tanah dibiarkan begitu saja setelah panen tanaman.

24 PRODUCTIVITY INDEX RATING OF SOILS Sumber: Productivity index rating of some soils in the Tolon/Kumbungu district of the Northern region of Ghana. Imoro Abukari Ziblim, Daniel Okai-Anti and E. Augustine Asmah. Journal of Soil Science and Environmental Management Vol. 3(6), pp. 154-163, 2012 Kandungan BOT The results of the study indicated low organic matter content in all the three series in the 0 to 20 cm and 20 to 40 cm sample depths (Table 3). Beberapa faktor mempengaruhi tinggi-rendahnya kandungan BOT, misalnya, kandungan BOT topsoil di daerah semi-arid sebesar 0.5 - 1.0% (Young, 1976) dan tanah-tanah berpasir biasanya mempunyai kandungan BOT lebih rendah dibandingkan dnegan tanah-tanah berliat (Biswas and Mukherjee, 1994). 1.Biswas TD, Mukherjee SK (1994). Textbook of soil science (2nd ed.) New Delhi India: Tale McGraw Hill Publishing Company Limited. pp. 414-422. 2.Young A (1976). Tropical soils and soil survey. Cambridge Geographical Studies, London, New York. p. 468.

25 PRODUCTIVITY INDEX RATING OF SOILS Kandungan BOT The low organic matter content may be due to the fact that the study sites have been intensively cultivated or are young fallow areas (2 to 5 years), where basically organic matter production or accumulation is low. Rendahnya kandungan BOT tanah juga disebabkan oleh panen biomasa tanaman secara kontinyu dan sedikitnya pengembalian BO sisa panen ke lahan. Faktor lainnya adalah tingginya kehilangan respirasi tanah akibat suhu tinggi (Brady and Weil, 1999), dan kehilangan erosi-tanah akibat tingginya intensitas hujan. Menurut Atkinson and Wright (1968), kandungan BOT biasanya menurun dengan penanaman yang terus-menerus. Dalal and Mayer (1990) juga melaporkan hal yang serupa. 1.Atkinson H, Wright K (1968). Comparative effect of keeping soil under continuous cultivation and keeping it under continuous grass. Soil Sci., 28: 30-42. 2.Dalal RC, Mayer RJ (1990). Long term trends in soil fertility under continuous cultivation and cereal cropping in Southern Queensland. Australian J., Soil Res., 24: 563-575.

26 PRODUCTIVITY INDEX RATING OF SOILS Sumber: Productivity index rating of some soils in the Tolon/Kumbungu district of the Northern region of Ghana. Imoro Abukari Ziblim, Daniel Okai-Anti and E. Augustine Asmah. Journal of Soil Science and Environmental Management Vol. 3(6), pp. 154-163, 2012 Korelasi positif antara kandungan BOT dengan kandungan liat dalam suatu tanah, menyatakan bahwa jumlah liat mempengaruhi kandungan BOT karena efek ikatan organic- inorganic dalam tanah. The mean CEC range of 8.04 to 15.36 cmolc kg-1 in the 0 to 20 cm depth and 3.33 to 4.92 cmolc kg-1 in the 20 to 40 cm depth fall within the range of 3 to 15 cmolc kg-1 (Müller- Sämann and Kotschi, 1994). 1.Müller-Sämann KM, Kotschi J (1994). Sustaining growth: Soil fertility management in tropical smallholders. Margraf Verlag, Weikersheim, Germany. pp. 81-138

27 PRODUCTIVITY INDEX RATING OF SOILS Sumber: Productivity index rating of some soils in the Tolon/Kumbungu district of the Northern region of Ghana. Imoro Abukari Ziblim, Daniel Okai-Anti and E. Augustine Asmah. Journal of Soil Science and Environmental Management Vol. 3(6), pp. 154-163, 2012 The range of 3.33 to 4.92 cmolc kg-1 is low when compared to the lower limit of average CEC at 5 cmolc kg-1 (Landon, 1991) but within the range 1 to 10 cmolc kg-1 (Foth and Ellis, 1997), which are common for kaolinitic clays. Mineral liat dalam tanah di lokasi penelitian adalah kaolinit. Nilai KTK rendah pada semua serie tanah. Analisis ragam menyatakan tidak ada efek perlakuan terhadap KTK tanah. Rataan KTK lebih tinggi pada serie tanah KS untuk kedalaman tanah 0 - 20 cm dan 20 - 40 cm, yang diikutui dengan seri tanah CS. 1.Foth HD, Ellis BG (1997). Soil fertility. Second edition. CRC Press Boca Raton, Florida, p. 290. 2.Landon JR (1991). Booker Tropical Soil Mannual. A Handbook for soil survey and agriculture land evaluation in the tropics and subtropics. Landon, J. R. (ed). Booker Tate, Thame, Oxon, UK, pp.58-125.

28 PRODUCTIVITY INDEX RATING OF SOILS Sumber: Productivity index rating of some soils in the Tolon/Kumbungu district of the Northern region of Ghana. Imoro Abukari Ziblim, Daniel Okai-Anti and E. Augustine Asmah. Journal of Soil Science and Environmental Management Vol. 3(6), pp. 154-163, 2012 Blanchart et al. (2007) reported that tropical sandy soils (or upper sandy horizons of tropical soils) have low cation exchange capacity. Rendahnya nilai KTK suatu tanah dapat disebabkan oleh beberapa faktor. Rendahnya kandungan BOT dan Liat dapat menyebabkan rendahnya nilai KTK tanah. 1.Blanchart E, Albrecht A, Bernoux M, Brauman A, Chotte JL, Feller C, Ganry F, Hien E, Manlay R, Masse D, Sall S, Villenave C (2007). Organic matter and biofunctioning in tropical sandy soils and implications for its management. FAO Corporate Document Repository, Management of tropical sandy soils for sustainable agriculture http://www.fao.org/docrep/010/ag125e/AG125E19.htm. Retrieved: 13/02/2012.

29 PRODUCTIVITY INDEX RATING OF SOILS Sumber: Productivity index rating of some soils in the Tolon/Kumbungu district of the Northern region of Ghana. Imoro Abukari Ziblim, Daniel Okai-Anti and E. Augustine Asmah. Journal of Soil Science and Environmental Management Vol. 3(6), pp. 154-163, 2012 Menurut Landon (1991), KTK merupakan sifat dari fraksi koloid tanah, terutama liat dan bahan organik. Hal ini mengakibatkan bahwa tanah- tanah yang miskin liat dan miskin BOT biasnaya mempunyai KTK yang rendah. Selain itu, tipe mineral liat juga berpengaruh terhadap nilai KTK tanah. Landon (1991) reported that kaolinite clay minerals tend to have very low CEC values and consequently, most tropical soils are basically kaolinitic as indicated earlier. Furthermore, the low CEC could be ascribed to the low pH values of the soils. At low pH values, the CEC is also generally low. 1.Landon JR (1991). Booker Tropical Soil Mannual. A Handbook for soil survey and agriculture land evaluation in the tropics and subtropics. Landon, J. R. (ed). Booker Tate, Thame, Oxon, UK, pp.58-125.

30 PRODUCTIVITY INDEX RATING OF SOILS Sumber: Productivity index rating of some soils in the Tolon/Kumbungu district of the Northern region of Ghana. Imoro Abukari Ziblim, Daniel Okai-Anti and E. Augustine Asmah. Journal of Soil Science and Environmental Management Vol. 3(6), pp. 154-163, 2012 pH Tanah The mean soil pH across the three series varies from very strongly acidic to strong acid in reaction in the 20 to 40 cm depth (4.4 to 5.0) and 0 to 20 cm depth (5.0 to 5.2) (Table 3). Kisaran pH ini berada di bawah nilai rata-rata 6.5 (Foth and Ellis, 1997) yang dianggap ideal bagi ketersediaan hara dalam tanah. Brady dan Weil (2002) menyatakan bahwa pH tanah mempengaruhi semua sifat-sifat kimia, fisika dan biologi tanah. 1.Brady NC, Weil RR (2002). The nature and properties of soil, 13th ed. Springer Netherlands, p. 249. 2.Foth HD, Ellis BG (1997). Soil fertility. Second edition. CRC Press Boca Raton, Florida, p. 290.

31 PRODUCTIVITY INDEX RATING OF SOILS Sumber: Productivity index rating of some soils in the Tolon/Kumbungu district of the Northern region of Ghana. Imoro Abukari Ziblim, Daniel Okai-Anti and E. Augustine Asmah. Journal of Soil Science and Environmental Management Vol. 3(6), pp. 154-163, 2012 Table 3. Some chemical properties of the soil series investigated within the sample depths of 0 to 20 cm and 20 to 40 cm.

32 PRODUCTIVITY INDEX RATING OF SOILS Sumber: Productivity index rating of some soils in the Tolon/Kumbungu district of the Northern region of Ghana. Imoro Abukari Ziblim, Daniel Okai-Anti and E. Augustine Asmah. Journal of Soil Science and Environmental Management Vol. 3(6), pp. 154-163, 2012 SERIE TANAH DAN INDEKS PRODUKTIVITAS (PI) Nilai PI suatu tanah menjadi indikator potensi produksi tanah itu. Nilai PI yang tinggi berarti potensi produktifnya juga tinggi. Misalnya, nilai PI tanah yang tinggi sebesar 8.32 x 10-4 pada serie tanah KS, dan nilai PI yang rendah pada serie tanah NS sebesar 0.72 × 10-4 (Table 4). These results presuppose that KS soils have higher productive potential. Productivity indices of 3.2 × 10-4, 3.2 × 10-4 and 19.2 × 10-4 for the 0 to 20 cm depth and 0.4 ×10-4, 1.6 x 10-4 and 1.6 × 10-4 for the 20 to 40 cm depth indicate that productivity potential of the soils decrease with depth. Lebih tingginya nilai PI pada tanah KS disebabkan oleh sifat-sifat tanah yg “baik” karena kandungan BOT, KTK dan kedalaman perakarannya lebih besar dibandingkan dnegan serie tanah lainnya.

33 PRODUCTIVITY INDEX RATING OF SOILS Sumber: Productivity index rating of some soils in the Tolon/Kumbungu district of the Northern region of Ghana. Imoro Abukari Ziblim, Daniel Okai-Anti and E. Augustine Asmah. Journal of Soil Science and Environmental Management Vol. 3(6), pp. 154-163, 2012 Table 4. Hasil perhitungan Indeks Produktif Serie Tanah dan Hasil Tanaman.

34 PRODUCTIVITY INDEX RATING OF SOILS Sumber: Productivity index rating of some soils in the Tolon/Kumbungu district of the Northern region of Ghana. Imoro Abukari Ziblim, Daniel Okai-Anti and E. Augustine Asmah. Journal of Soil Science and Environmental Management Vol. 3(6), pp. 154-163, 2012 Figure 1. The yield (Kg/ha) of maize in the soil series.

35 PRODUCTIVITY INDEX RATING OF SOILS Sumber: Productivity index rating of some soils in the Tolon/Kumbungu district of the Northern region of Ghana. Imoro Abukari Ziblim, Daniel Okai-Anti and E. Augustine Asmah. Journal of Soil Science and Environmental Management Vol. 3(6), pp. 154-163, 2012 KESIMPULAN Sifat-sifat fisika dan kimia tanah dapat digunakan untuk mengkuantifikasikan produktivitas tanah. Indeks Produktivitas Storie (1978) cukup efektif untuk mengkuantifikasikan produktivitas tanah, modifikasinya ternyata juga lebih efisien terutama dnegan memasukkan parameter kandungan BOT, pH tanah dan KTK, serta menggunakan berbagai jenis tanah. This study therefore, increased the validity of the model. Hence, it is recommended that soil management practices such as amendment of acid soils through liming, incorporation of organic residue into the soil to improve upon the organic matter status, addition of inorganic fertilizers and crop rotation could be adopted.

36 PRODUCTIVITY INDEX RATING OF SOILS Sumber: Productivity index rating of some soils in the Tolon/Kumbungu district of the Northern region of Ghana. Imoro Abukari Ziblim, Daniel Okai-Anti and E. Augustine Asmah. Journal of Soil Science and Environmental Management Vol. 3(6), pp. 154-163, 2012

37 PRODUCTIVITY INDEX RATING OF SOILS Sumber: Productivity index rating of some soils in the Tolon/Kumbungu district of the Northern region of Ghana. Imoro Abukari Ziblim, Daniel Okai-Anti and E. Augustine Asmah. Journal of Soil Science and Environmental Management Vol. 3(6), pp. 154-163, 2012