Bahr, E.; Chamba Zaragocin, D.; Fierro Jaramillo, N.; Witt, A. & Makeschin, F. (2014): <b>Modeling of soil nutrient balances, flows and stocks revealed effects of management on soil fertility in south Ecuadorian smallholder farming systems</b>. <i>Nutrient Cycling in Agroecosystems</i> <b>-</b>, -.
Resource Description
Title:
Modeling of soil nutrient balances, flows and stocks revealed effects of management on soil fertility in south Ecuadorian smallholder farming systems
FOR816dw ID:
1308
Publication Date:
2014-11-21
License and Usage Rights:
PAK 823-825 data user agreement. (www.tropicalmountainforest.org/dataagreementp3.do)
email:
makeschin <at> t-online.de
Pienner Str. 19
Dresden University of Technology
Faculty of Forest, Geo and Hydro Sciences
Institute of Soil Science and Site Ecology
Postfach 1117
01735 Tharandt
Germany
Abstract:
Linking nutrient balances and flows to soil<br/>
nutrient stocks creates a valuable indicator for sustainability<br/>
assessment in agricultural land-use systems.<br/>
Therefore, we investigated the impact of management<br/>
on soil fertility at farm/field scale using the Nutmon<br/>
approach. A detailed methodology for the adaptation<br/>
of the difficult-to-quantify flows to the local conditions<br/>
is described. Research was carried out in the three<br/>
farming systems of Yantzaza (low-external-input), El<br/>
Tambo (irrigated cash crops) and San Lucas (integrated<br/>
nutrient management) in southern Ecuador. For<br/>
each land-use within a farm (annual and perennial<br/>
crops, pasture, forest), soil nutrient balances and flows<br/>
were modeled with Nutmon and soil nutrient stocks<br/>
were calculated for NPK. Soil nutrient balances were<br/>
evaluated using potential socio-economic and soil<br/>
fertility explanatory variables. Balances for the different<br/>
land-uses in the three research areas varied between<br/>
-151 to 66 kg ha-1 a-1 for N, -4 to 33 kg ha-1 a-1 for P and -346 to 39 kg ha-1 a-1 for K and were mainly negative. Up to 70 % of the balances’ variability was explained by soil fertility variables and financial flows. Highest external inputs existed in<br/>
land-uses with a strong market orientation. Land-uses<br/>
benefiting from a surplus of within-farm flows had the<br/>
highest soil nutrient stocks. The focus on N fertilization<br/>
induced highly negative PKbalances in annual crops of<br/>
El Tambo. In contrast, the application of organic<br/>
fertilizers and nutrient recycling in San Lucas resulted<br/>
in positive NP balances particularly for perennial<br/>
crops. NP balances in annual crops of Yantzaza were<br/>
most negative due to nonexistent fertilization, leaching<br/>
and burning of crop residues. A non-sustainable landuse<br/>
of annual crops in Yantzaza was illustrated by total<br/>
N stock decreases of 4.9 % a-1 and decreased soil<br/>
organic carbon stocks to 85 % of adjacent forest sites.<br/>
Results indicated a potential risk regarding sustainable<br/>
management of soils in the research area and provide a<br/>
basis for policy and decision makers to develop<br/>
appropriate management strategies.
