Sediment-bound soil nutrient loss under simulated rainfall

Sediment-bound soil nutrient loss under simulated rainfall Abstract:  Soil erosion is not only the loss of soil particles, but also the loss of sediment-bounded nutrients and elements. One the principle methods of the assessment of soil erosion and nutrient loss, is to use rainfall simulators. The aim of this study was to evaluate the role of land-use, slope gradient and direction on the loss of soil nutrients in Kechik Coupled Watershed Site in Golestan Province using rainfall simulation. In order to determine the sediment’s content of potassium, nitrogen and phosphorous, flame photometry, Kjedalhl and spectrophotometry methods were used. To estimate organic carbon, the Walkey-Black method was exercised. Given the results, the highest obtained values of nitrogen loss was attributed to the agricultural land-use. This follows rangeland and forest; although, with a slight difference. Potassium loss was greatest in the rangelands by 0.15 t.ha-1, and agriculture and forest ranked second and third. Soil nutrient loss in terms of phosphorus, was maximum in the forest land-use and then respectively, agriculture and rangelands. Soil organic carbon loss was maximally measured in the forest, rangeland and agriculture, respectively. In this study, two slope classes of 0-20 and 20-40 was considered in the forest and rangeland land-uses, while the classification of slope gradient in agricultural land-use was in different two classes of 0-15 and 15-30. According the findings, soil nitrogen, phosphorus and organic matter loss was highest in case of the second slope gradient class (20-40% in rangelands and agricultural fields; 20-40% in forest land-uses) of all land-uses and aspects. Interestingly, soil potassium loss was greatest in the first slope class. Northern slope directions had the highest soil nutrient loss compared with the southern direction in all land-use types. The findings of this study put emphasis on the land-use management and primarily underlines the role of agricultural land-uses. Keywords:  Nutrient loss, land-use, Kechik, erosion, BSTF1, Golestan Yagis simulasyonu modeli kullanarak toprak ve besin maddesi kayiplarinin hesaplanmasi Ozet:  Toprak erozyonu sadece toprak parcaciklari kaybi degil, ayni zamanda besin ve elementlerin de kaybidir. Toprak erozyonu ve besin kaybini olcmek icin yagis simulatorleri kullanmaktir. Bu calismanin amaci, arazi kullanimi ve egim parametrelerini kullanarak Gulistan Eyaleti- Kechik su havzasinda yagis simulasyonu modeli kullanarak toprak ve besin kaybini hesaplamaktir. Sedimentlerdeki potasyum, azot ve fosfor icerigini belirlemek icin, Kjedalhl ve spektrofotometri yontemleri kullanilmistir. Organik karbon tahmini icin ise Walkey-Black Metodu kullanilmistir. Sonuclar goz onune alindiginda, azot kaybinin en yuksek oldugu alanlar tarimsal arazilerdir. Bunu; kucuk bir fark ile meralar ve orman izlemektedir. Potasyum kaybi 0.15 t.ha-1 ile en fazla meralarda gorulmus, tarim ve orman alanlari ise ikinci ve ucuncu sirada yer almistir. Fosfor yonunden toprak besin kaybi, sirasiyla, tarim ve meralar daha sonra orman arazisi kullaniminda maksimum olarak olculmustur. Bu calismada, orman ve mera arazi kullanimlarinda kullanilan egim siniflari 0-20 ve 20-40 olarak; tarimsal arazi kullaniminda ise 0-15 ve 15-30 olarak kabul edilmistir. Bulgular, topraktaki azot, fosfor ve organik madde kaybinin ikinci egim sinifinda en yuksek oldugunu gostermistir. Bu calismanin bulgulari basta arazi kullanim yonetimine vurgu yapmakta; tarimsal arazi kullanimlarinin etkisini ele almaktadir. Anahtar Kelimeler:  Besin kaybi, arazi kullanimi, Kechik, erozyon, BTF1, Gulistan Received (Gelis):  08.04.2016 -  Revised (Duzeltme):  24.05.2016 - Accepted (Kabul):  06.06.2016 Cite (Atif):  Sheikh, V.B., Shalamzari, M.J., Farajollahi, A., 2017. Sediment-bound soil nutrient loss under simulated rainfall.  Journal of the Faculty of Forestry Istanbul University  67(1): 37-78. DOI: 10.17099/jffiu.95610