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Topographic Controls on Soil Nutrient Variations in a Silvopasture System

Author:
Kabindra Adhikari, Phillip R. Owens, Amanda J. Ashworth, Thomas J. Sauer, Zamir Libohova, Jenny L. Richter, David M. Miller
Source:
Agrosystems, geosciences & environment 2018 v.1 no.1 pp. -
ISSN:
2639-6696
Subject:
boron, calcium, copper, digital elevation models, iron, landscapes, magnesium, manganese, nutrient management, pasture management, phosphorus, plant micronutrients, potassium, prediction, production technology, silvopastoral systems, sodium, soil nutrients, sulfur, topographic slope, topsoil, total nitrogen, valleys, zinc, Arkansas
Abstract:
Topography plays a crucial role in spatial distribution of nutrients in soils; however, studies to quantify topographic influence on soil nutrient distribution from a silvopasture system are mostly lacking. To address this question, a 4.3-ha silvopasture site in northwest Arkansas was selected and a total of 51 topsoil (0–15 cm thickness) samples were collected and analyzed for primary (total N [TN], P, K), secondary (Ca, Mg, S), and micronutrients (Fe, Zn, Cu, Mn, B, Na). Topographic information was acquired from 12 terrain attributes derived from a 1-m digital elevation model. The prediction model was based on random forest. Results showed TN, S, and P were best predicted, whereas Cu, Ca, and Mn had the lowest prediction performance. Levels of S, Ca, Zn, Fe, and TN increased with SAGA wetness index, valley depth, flow accumulation, and multi-resolution valley bottom flatness index. Normalized height and slope height were positively related to Na but negatively to B and Cu distribution. Aspect had a positive influence on P and Mg concentrations. Based on terrain attributes, the study site could be divided into four topographic functional units (TFU), namely A, B, C, and D; TFU A had the highest nutrients present, whereas TFU B had the lowest P, K, Zn, Cu, Fe, and Ca but highest Na content. However, Mn, Mg, and B did not vary among TFUs. This study affirmed topographic influences on soil nutrient distribution, and the resulting continuous soil nutrient maps are useful for fine-tuning production systems through optimum nutrient and pasture management.
Agid:
6550427
Handle:
10113/6550427