Crop protection
“Best bet” Land-use Systems
Country reports
Alternatives to Slash-and-Burn in Brazil
Agronomic Sustainability
Unique id: IDAV4SCE
Source file: D:\Projects\ASB\ASB Country and Thematic reports\Brazil country report\ASB Brazil Summary Report.xml
Authors: S. Vosti, C. L. Carpentier, J. Witcover, . Carvalho dos Santos, E. Muñoz Braz, J. Ferreira Valentim, S. J. de Magalhães de Oliveira, C. Palm, F. de Souza Moreira, A. Cattaneo, A. Gillison, A. Mansur Mendes, V. Rodrigues, T. C. de Araújo Gomes, M. V. Neves d’Oliveira, E. do Amaral, S. Fujisaka, C. Castilla, T. Tomich, D. Bignell, D. Gonçalves Cordeiro, A. Hermes Vieira, R.S. Correira da Costa, M. Faminow, M. Locatelli, M. Swift, S. Weise, M. van Noordwijk, N. Sampaio, I. L. Franke, H. J. Borges de Araujo, L. M. Rossi, E. Barros, B. Feigl, S.P. Huang, J. Cares, C. Pinho de Sá, . Carneiro, P. Woomer
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Attack by weeds, pests and diseases can be another important agronomic constraint to sustainable production. An attempt was made to identify potential crop protection problems; although no field observations were made. Assessments of whether or not weeds are or could become a major constraint in different LUS (in the absence of additional labour and/or technical inputs to combat them) were undertaken, based on the field experience of researchers and using the data from the above-ground biodiversity working group. A similar assessment was made for pest and disease problems, using the measurements of nematodes made by the below-ground biodiversity group.
The results for the
The first point to note is that forests, obviously, face no agronomic sustainability problems. Overall, the lowest variability (between maximum and minimum recorded values) in the indicators was observed for the forest plots, and the highest for annual crop and pasture systems.
Table 9. Indicators of soil structure
|
System |
Site |
Bulk density |
Deficit C |
Soil active carbon |
Soil exposure |
|
|
Theobroma |
1.34 |
0.66 |
2.22 |
85 |
|
|
RECA |
1.08 |
0.94 |
2.26 |
? |
|
|
Pedro Peixoto |
1.38 |
0.54 |
0.72 |
90 |
|
|
Index |
0 |
0 |
0 |
0 |
|
Fallow |
Theobroma |
1.13 |
0.74 |
2.22 |
92 |
|
|
Theobroma |
1.34 |
0.57 |
1.65 |
? |
|
|
Pedro Peixoto |
1.12 |
0.82 |
0.58 |
95 |
|
|
Index |
0 |
-0.5 |
0 |
0 |
|
Agroforest |
Ji-Paraná |
1.02 |
0.56 |
1.33 |
45 |
|
|
Ji-Paraná |
1.18 |
0.63 |
0.96 |
35 |
|
|
RECA |
1.11 |
0.61 |
0.53 |
40 |
|
|
Index |
0 |
0 |
-0.5 |
-0.5 |
|
Pasture |
Ji-Paraná |
1.21 |
0.48 |
0.77 |
95 |
|
|
Theobroma |
1.30 |
0.58 |
2.23 |
? |
|
|
Pedro Peixoto |
1.53 |
0.64 |
0.88 |
95 |
|
|
Index |
-1 |
0 |
0 |
0 |
|
Annual crops |
Theobroma |
1.24 |
0.69 |
1.87 |
15 |
|
|
Theobroma |
1.31 |
0.64 |
1.52 |
? |
|
|
Pedro Peixoto |
1.17 |
0.72 |
0.57 |
? |
|
|
Index |
-0.5 |
-0.5 |
-0.5 |
-1.0 |
Notes:
‘?’
indicates no conclusions could be drawn given available evidence and/or
experience.
RECA is a cooperative
located in western Rondônia that specialized in a specific agroforestry system.
Source: Working group
document
Table 10. Indicators
of soil biological health
|
System |
Site |
Mycorrhiza |
Nitrogen-fixing
bacteria |
|||
|
Vigna |
Other |
Various |
||||
|
|
|
|
|
|
|
|
|
|
Theobroma |
184 spores |
8
species |
0 |
-0.5 |
0 |
|
|
RECA |
130 spores |
6
species |
-1 |
-0.5 |
-0.5 |
|
|
Pedro
Peixoto |
100 spores |
7
species |
0 |
-0.5 |
-0.5 |
|
|
Index |
|
0 |
|
|
-0.5 |
|
|
|
|
|
|
|
|
|
Fallow |
Theobroma |
120 spores |
7
species |
0 |
-0.5 |
0 |
|
|
Theobroma |
180 spores |
8
species |
0 |
-0.5 |
-0.5 |
|
|
Pedro
Peixoto |
80 spores |
5
species |
0 |
-1 |
-0.5 |
|
|
Index |
|
0 |
|
|
-0.5 |
|
|
|
|
|
|
|
|
|
Agroforest |
Ji-Paraná |
40 spores |
7
species |
-1 |
-1 |
-0.5 |
|
|
Ji-Paraná |
110 spores |
4
species |
0 |
-0.5 |
-0.5 |
|
|
RECA |
40 spores |
4
species |
0 |
-0.5 |
0 |
|
|
Index |
|
-0.5 |
|
|
-1 |
|
|
|
|
|
|
|
|
|
Pasture |
Ji-Paraná |
91 spores |
5
species |
0 |
-0.5 |
-0.5 |
|
|
Theobroma |
427 spores |
4
species |
0 |
-0.5 |
0 |
|
|
Pedro
Peixoto |
121 spores |
5
species |
0 |
0 |
0 |
|
|
Index |
|
-0.5 |
|
|
0 |
|
|
|
|
|
|
|
|
|
Annual crops |
Theobroma |
150 spores |
6
species |
0 |
-0.5 |
-0.5 |
|
|
Theobroma |
60 spores |
5
species |
-1 |
-0.5 |
0 |
|
|
Pedro
Peixoto |
360 spores |
8
species |
-1 |
-0.5 |
-0.5 |
|
|
Index |
|
0 |
|
|
-1 |
Source: Working group
document
Table 11. Indicators
of crop protection constraints
|
LUS |
Site |
Disease
problem |
Weed problem |
|
|
|
|
|
|
|
Theobroma |
|
0.17 |
|
|
RECA |
|
0.10 |
|
|
Pedro Peixoto |
|
? |
|
|
Index |
0 |
0 |
|
|
|||
|
Fallow |
Theobroma |
|
0.73 |
|
|
Theobroma |
|
? |
|
|
Pedro Peixoto |
|
0.30 |
|
|
Index |
0 |
0 |
|
|
|||
|
Agroforest |
Ji-Paraná |
|
0.64 |
|
|
Ji-Paraná |
|
0.77 |
|
|
RECA |
|
0.50 |
|
|
Index |
0 |
-0.5 |
|
|
|||
|
Pasture |
Ji-Paraná |
|
0.98 |
|
|
Theobroma |
|
? |
|
|
Pedro Peixoto |
|
0.95 |
|
|
Index |
-0.5 |
-1.0 |
|
|
|||
|
Annual crop |
Theobroma |
|
0.85 |
|
|
Theobroma |
|
? |
|
|
Pedro Peixoto |
|
? |
|
|
Index |
-0.5 |
-1.0 |
Source: Working group document
Table 12. Agronomic sustainability indicators
|
|
|||||
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
Bulk
density |
1.08 – 1.38 |
1.12 – 1.34 |
1.02 – 1.18 |
1.21
– 1.53 |
1.17 – 1.31 |
|
C
deficit |
0.54 – 0.94 |
0.57 – 0.82 |
0.56 – 0.63 |
0.48 – 0.64 |
0.69 – 0.72 |
|
C-
active soil |
0.72 – 2.26 |
0.58 – 2.22 |
0.53 – 1.33 |
0.77 – 2.23 |
0.57 – 1.87 |
|
Soil
exposure |
85 – 90 |
92 – 95 |
35 – 45 |
95 |
15 |
|
|
|
|
|
|
|
|
Nutrient balance |
|
|
|
|
|
|
NNE
– N |
-0.76 |
-4.1/+12.4 |
-60/-24.5 |
-4.91 |
-24.99 |
|
NNE
– P |
-0.01 |
-
2.9/-6.8 |
-23/-2.5 |
-1.15 |
-2.71 |
|
NNE
– K |
-0.18 |
-
4.9/10.5 |
-31.5/-12 |
-1.53 |
-11.43 |
|
|
|
|
|
|
|
|
Soil biota |
|
|
|
|
|
|
Mycorrhizae |
8 – 6 |
8 – 5 |
7 – 4 |
5 – 4 |
8 – 5 |
|
Rhizhobia |
- 0.5 |
- 0.5 |
1 |
0 |
1 |
|
|
|
|
|
|
|
|
Crop protection |
|
|
|
|
|
|
Weed
problem |
0.17 – 0.10 |
0.30 – 0.73 |
0.50 – 0.77 |
0.95
– 0.98 |
0.85 |
|
Nematodes |
0 |
0 |
0 |
- 0.5 |
- 0.5 |
Notes:
Colours: Dark-grey means no problems;
black = moderate problems; bold = severe problems.
Units: bulk density (g/cm3); NNE (kg/ha/yr); mycorrhizae (number of species); rhizhobia (index); weed problem (data provided under above-ground biodiversity) and nematodes (index).
Source: Mendes et al (1999)
In the case of pastures, in addition to soil compaction, pests and diseases generally increase with the age and intensity of use of the pasture. Currently, spittle bug and brown plant hoppers are major pests in pastures. In the past year, many pastures containing Brachiaria brizantha grass have died out, posing a serious threat to sustainability (Valentim et al, 2000). However, soil carbon is higher in pastures than in some other measured systems.
The sustainability concerns for the agroforestry systems are related to nutrient balance, as many nutrients are exported in the harvested products without being returned. The simple nutrient balance shows significant negative values for N, P and K. The scored indicators also suggest problems related to the disturbance of mycorrhizae. Taking into account all criteria, the forest systems were rated as most sustainable, followed by fallow systems, although these did have some nutrient balance problems. Cropping systems were rated as problematic with respect to all but one of the criteria (mycorrhizae). This is a critical finding, since annual cropping systems are widespread at the Brazilian benchmark sites.