Agriculture, Ecosystems and Environment 83 2001 65–81
Ecological lessons and applications from one century of low external-input farming in the
pampas of Argentina
E.F. Viglizzo
a,b,∗
, F. Lértora
b
, A.J. Pordomingo
a
, J.N. Bernardos
c
, Z.E. Roberto
a
, H. Del Valle
b
a
INTA, Centro Regional La Pampa, 6300 Santa Rosa, La Pampa, Argentina
b
CONICETINTA, Centro Regional La Pampa, 6300 Santa Rosa, La Pampa, Argentina
c
Univ. La Pampa, Fac. Ciencias Exactas y Naturales, 6300 Santa Rosa, La Pampa, Argentina Received 7 July 1999; received in revised form 5 January 2000; accepted 15 March 2000
Abstract
Ecology may benefit from long term, large scale experiments on low intensity farming to test theoretical principles and convert them into practical lessons. One century of land conversion in the Argentine pampas, and its effect on critical
ecological properties, were analysed and discussed. Land transformation has resulted in significant changes of land use, land cover, energy flow, nutrient dynamics, hydrology, and the trade-offs between productivity, stability and sustainability.
The analytical procedure involved the complementary utilisation of different data sources and approaches. The study was focused on large geographical scales: the entire pampas and its five ecoregions. Results were interpreted under the theoretical
framework of succession in ecology. The historical conversion of natural grasslands into cultivated grasslands and croplands was not homogeneous, determining a variety of land use and land cover patterns. Due to its higher productivity, much more
energy, nutrients and water were mobilised in the rolling pampas than in the other ecoregions. This study provides lessons about how the energy flow, the nutrient dynamics and the hydrological process are modified by land transformation under
low external-input conditions. Technical coefficients to be applied in emerging fields of environment administration such as ecological-monitoring, environmental accounting and auditing, agro-ecological certification, land evaluation and allocation,
and land management, can also be supplied by this kind of studies. © 2001 Elsevier Science B.V. All rights reserved.
Keywords: Low external-input farming; 100-year farming; Ecological applications; Pampas; Argentina
1. Introduction
Ecology is an evolving collection of principles with application to practical fields, such as agriculture,
forestry, fisheries, natural lands and medicine. Ecolo-
∗
Corresponding author. Tel.: +54-2954-434-222; fax: +54-2954-434-222.
E-mail address: eviglizssdnet.com.ar E.F. Viglizzo.
gical principles cannot always be tested by experi- mental research because of a the large areas and long
time periods that need experimental control Tilman, 1990, b the financial and managerial limitations to
designing long term treatments for large areas Car- penter et al., 1995, and c the difficulty to find areas
with homogenous pre-treatment history, as well as un- treated control areas for reliable comparisons Likens,
1992. Although surveys are considered acceptable
0167-880901 – see front matter © 2001 Elsevier Science B.V. All rights reserved. PII: S 0 1 6 7 - 8 8 0 9 0 0 0 0 1 5 5 - 9
66 E.F. Viglizzo et al. Agriculture, Ecosystems and Environment 83 2001 65–81
Table 1 Comparison of farming intensity in three countries that differ in resources and external-inputs use
a
Argentina USA
The Netherlands Cropland area ×1000 ha
35750 189915
924 Average yield kgha
2257 4383
6641 Annual use of fertiliser kgha
4 93
748 Annual use of pesticides kgha
0.40 1.97
10.47 Tractors number100 ha
0.58 2.46
20.58 Irrigated cropland
5 10
59 Cattle numberkm
2
18.79 10.41
130.06 Pigs numberkm
2
1.46 4.97
375.54
a
Source: WRI 1990 after various sources.
options to test hypothesis and theories when experi- mentation is not possible, the applicability of poorly
tested principles is cause of concern among ecologists Pienkowski and Watkinson, 1996.
Ecology may benefit from low external-input farm- ing to test principles and deliver practical lessons.
The pampas of Argentina represent a large scale, long term, and non-controlled experiment in low input
farming that started at the end of the 19th century and lasted until the beginning of the 1990s. Until
then, lands had maintained their pristine condition with negligible human intervention. One century of
land transformation Pizarro, 1997; Solbrig, 1997 in different ecoregions Ghersa et al., 1998 was a valu-
able source of variability that has comprised different crop, cattle, and crop-cattle production activities.
Low external-input farming refers to systems that use reduced quantities of inputs, such as fertiliser,
pesticide, irrigation, high-yielding crops, concentrate feed, machinery, etc. Matson et al., 1997, that in-
volve fossil energy in manufacturing or operation. In comparison with more intensive schemes of USA
and the Netherlands, the low input use and crop yields in Argentina before the 1990s are shown in
Table 1.
This article provides an overview of one century of land transformation under low input conditions in the
pampas, and its consequences on ecological structures like land-use and land-cover, and functions, such as
energy flow, nutrient dynamics, hydrological process, and the trade-offs between productivity, stability and
sustainability. The study focuses on large geographi- cal scales: the pampas region, and its corresponding
five ecoregions. The key expected outcomes of this investigation are to a interpret the ecological dynam-
ics of the region, and b obtain technical coefficients for application, such as land evaluation, allocation and
management.
2. Methods
