Explorations based on the four scenarios

Explorations for the eight farms were conducted for scenarios S1 to S4. From the current system (S0) to scenario S3 the number of possible cropping systems increased sequentially, and FarmDESIGN was used to find combinations of areas that optimized farm performance for the three objectives maximize family income, minimize own labour and maximize OM balance, simultaneously. Scenario S4 comprised the set of cropping systems of S3 plus animal husbandry on those farms that did not have animals to start with. Decision variables comprised hectares of cropping activities and, for S4, number of goats and cows and their replacement rate. The results demonstrate that improvements are feasible for family income, OM balance and required family labour as illustrated for farm A3 in Scenario 4 (Figure 3). The relation between labour requirement and the other two objectives was similar for all farms: relatively small differences between best and worst values of labour requirement. As a result, in the rest of this section we concentrate on the trade-off between the other two objectives, which was however calculated including the labour balance objective. The results are shown in Figure 4 and Table 8 for each farm and for each of the four scenarios.

156

Figure 1. Family income for eight smallholder farms in Costa Chica, Mexico, for different maize-based cropping systems. Grey bars: family income from agriculture. White bars: family income from the PROCAMPO subsidy (MX $1,030 ha^-1). The horizontal line represents the basic food basket (CONEVAL, 2012) for the particular farm family. For details on the maize-based cropping systems described in the legend see Table 4.

0

Cu(Fcr) Cu+k(Fcr) S(Fcr) S+K(Fcr) R(Fcr) E(Fcr) E(Vcr) E(F-Vcr) E(FCr) E(VCr) E(F-VCr) E(FCR) E(VCR) E(F-VCR)

Family income (MX$ yr-1)

Cu(Fcr) Cu+k(Fcr) S(Fcr) S+K(Fcr) R(Fcr) E(Fcr) E(Vcr) E(F-Vcr) E(FCr) E(VCr) E(F-VCr)

Family income (MX$ yr-1)

Cu(Fcr) Cu+k(Fcr) S(Fcr) S+K(Fcr) R(Fcr) E(Fcr) E(Vcr) E(F-Vcr) E(FCr) E(VCr) E(F-VCr)

Family income (MX$ yr-1)

Cu(Fcr) Cu+k(Fcr) S(Fcr) S+K(Fcr) R(Fcr) E(Fcr) E(Vcr) E(F-Vcr) E(FCr) E(VCr) E(F-VCr)

Family income (MX$ yr-1)

Cu(Fcr) Cu+k(Fcr) S(Fcr) S+K(Fcr) R(Fcr) E(Fcr) E(Vcr) E(F-Vcr) E(FCr) E(VCr) E(F-VCr) E(FCR) E(VCR) E(F-VCR)

Family income (MX$ yr-1)

Cu(Fcr) Cu+k(Fcr) S(Fcr) S+K(Fcr) R(Fcr) E(Fcr) E(Vcr) E(F-Vcr) E(FCr) E(VCr) E(F-VCr) E(FCR) E(VCR) E(F-VCR)

Family income (MX$ yr-1)

Cu(Fcr) Cu+k(Fcr) S(Fcr) S+K(Fcr) R(Fcr) E(Fcr) E(Vcr) E(F-Vcr) E(FCr) E(VCr) E(F-VCr) E(FCR) E(VCR) E(F-VCR)

Family income (MX$ yr-1)

Cu(Fcr) Cu+k(Fcr) S(Fcr) S+K(Fcr) R(Fcr) E(Fcr) E(Vcr) E(F-Vcr) E(FCr) E(VCr) E(F-VCr) E(FCR) E(VCR) E(F-VCR)

Family income (MX$ yr-1)

X4

157

Figure 2. Trade-offs among family income, regular labour requirements and OM balance assuming that eight smallholder farms dedicate their entire cropping area to a single maize-based cropping system (MBCS). Results are expressed as averages across farms. Bars indicate standard errors. Panels on the left concern farms with animals, farms on the right without animals. MBCS codes: A: Cu(Fcr), B: Cu+K(Fcr), C: S(Fcr), D: S+K(Fcr), E: R(Fcr), F: E(Fcr), G: E(Vcr), H: Vcr), I: E(FCr), J: E(VCr), K: VCr), L: E(FCR); M: E(VCR), N: E(F-VCR). For details on the maize-based cropping systems described in the legend see Table 4.

-500

0 5000 10000 15000 20000 25000 30000

OM (kg per farm)

3900 4000 4100 4200 4300 4400 4500

OM (kg per farm)

0 10000 20000 30000 40000 50000 60000

OM (kg per farm)

0 10000 20000 30000 40000 50000 60000

Labour (h yr-1)

Family income (MX$ per farm)

C

158

Figure 3. Illustration of the trade-offs among family income, regular labour input and OM balance on farm A3 for explorations based on Scenario 4. The open circle corresponds to current MBCS. Closed circles represent alternative farming systems. The triangle in the top panel illustrates the procedure used to arrive at Figure 4.

For Scenario S1, maximum family income was mostly associated with the current fertilizer strategy plus K (Table 8). On two farms, MBCS based on subsidized rates of fertilizer were selected, and on the farm with the largest number of animals (A3) canavalia was grown on 40% of the area. To maximize OM balance, on some farms MBCS with current or subsidized rates of fertilizer rates dominated, always with a supplementation of K. On other farms moderate fertilizer rates were combined with canavalia and residue retention (E(FCR)). For Scenario S2 the inclusion of vermicompost was selected among the options that maximized OM balances. To maximize family income the land use systems selected were similar to those for S1.

For Scenario S3 the R(Fcr) option that included the largest fertilizer rates resulting in the largest maize biomass and yield was selected on all farms to maximize family income. Large biomass and hence residue production by R(Fcr) also made it the option

0 200 400 600 800 1000

5000 10000 15000 20000 25000

OM (Kg ha-1)

3400 3500 3600 3700

5000 10000 15000 20000 25000

Labour (h yr-1)

Family income (MX$ per farm)

3400 3500 3600 3700

0 200 400 600 800 1000

OM (kg ha^-1)

Ο

Ο

159

Table 8. Major MBCS and numbers of animals selected to maximize family income or organic matter balance (OM) under four intensification scenarios. For explanation of abbreviations of the MBCS see Table 4. FarmsCharacteristicsCurrent S0Scenario S1 Scenario S2 Scenario S3 Scenario S4 Family IncomeOMFamily IncomeOMFamily IncomeOMFamily IncomeOM A1MBCS (ha)Cu(Fcr)S+K(Fcr)* (100) S+K(Fcr) (100) S+K(Fcr) (100) E(F-Vcr) (92)R(Fcr) (100) R(Fcr) (100) R(Fcr) (66) Can (34)R(Fcr) (62) Can (38) Animals 0 0 0 0 0 0 0 1315 A2MBCSCu(Fcr)Cu+k(Fcr) (100) Cu+k(Fcr) (99)E(F-Vcr) (61) S+K(Fcr) (17) Cu+k(Fcr) (17)E(F-Vcr) (60) E(F-VCr) (38)R(Fcr) (55) E(F-Vcr) (38)E(F-Vcr) (53) E(F-VCr) (47)R(Fcr) (95)E(F-VCr) (85) Animals 121212121212120 25 A3MBCSCu(Fcr)S (Fcr) (45) Can (39) S+K(Fcr) (15)S+K(Fcr) (57) S(Fcr) (33)S+K(Fcr) (44) S(Fcr) (31)E(F-Vcr) (85) Can (14)R(Fcr) (67) Can (33)E(F-Vcr) (87) Can (13)R(Fcr) (81) Can (13)E(F-Vcr) (59) E(F-VCr) (39) Animals 282828282828282221 A4MBCSCu(Fcr)Cu+k(Fcr) (100)E(FCr) (85) Cu+k(Fcr) (15)E(F-VCr) (100) E(F-VCr) (100) R(Fcr) (100) E(F-VCr) (100) R(Fcr) (93)E(F-VCr) (100) Animals 7 7 7 7 7 7 0 0 X1MBCSCu(Fcr)Cu+k(Fcr) (100)E(FCR) (100)Cu+k(Fcr) (100)E(F-VCR) (100)R(Fcr) (100) E(F-VCR) (100)R(Fcr) (100) R(Fcr) (100) Animals 0 0 0 0 0 0 7 7 X2MBCSCu(Fcr)Cu+k(Fcr) (100)E(FCR) (100)Cu+k(Fcr) (100)E(F-VCR) (100)R(Fcr) (100) E(F-VCR) (100) Animals 0 0 0 0 0 0 X3MBCSCu(Fcr)Cu+k(Fcr) (100)E(FCR) (100)Cu+k(Fcr) (100)E(F-VCR) (100)R(Fcr) (100) E(F-VCR) (100)R(Fcr) (100) E(F-Vcr) (73) R(Fcr) (13) Can (13) Animals 0 0 0 0 0 0 0 0 16 X4MBCSCu(Fcr)Cu+k(Fcr) (100)Cu+k(Fcr) (100) Cu+k(Fcr) (100)E(F-VCR) (58) E(F-VCr) (33)R(Fcr) (100) R(Fcr) (100) Animals 0 0 0 0 0 0 0

160

Figure 4. Relationship between family income and OM balance for the exploration of four scenarios on eight farms. The horizontal dotted line represents the basic food basket (CONEVAL, 2012) for the total farm family.

0

161

that maximized OM balance on two of the eight farms. On the other farms maximizing OM balance required MBCS relying on canavalia and/or vermicompost. Optimization of number of animals in Scenario S4 maintained R(Fcr) as the best MBCS to maximize family income. Only on half of the farms animal husbandry was a means to increase family income. However, animal husbandry together with the application of vermicompost with or without canavalia (E(F-VCr) and E(F-Vcr)) were important to maximize OM balances (Table 8).

Trade-off triangles were constructed for the objectives family income and OM balance by linearly connecting the current farming system with those that exhibited best performance in each of the objectives, as illustrated in Figure 3. The trade-off triangles (Figure 4) show that as the number and type of land use options increases from scenario S0 to S4, the trade-off frontier shifts outward. Both family income and OM balance can be improved, although with large differences among the farms, as revealed by the size of the triangles. The triangles are not congruent, indicating that the trade-offs between the objectives change when progressing through the scenarios. For some scenarios and farms narrow triangles were found (e.g. farm A1, scenario S3;

farm X4, scenario S3) indicating that trade-offs were replaced by (a few) optimal solution(s).

4. Discussion

This study set out to study options for improving socio-economic performance and resource use of smallholder livelihoods in the Costa Chica by bringing together information on alternative maize-based cropping systems and animal husbandry in a context of actual farms. The study addressed socio-economic performance in terms of family income and use of regular labour, and evaluated resource use in terms of changes in the soil OM balance.

4.1. Opportunities for improving family income, OM balance and labour balance