Systematic design and evaluation of crop rotations enhancing soil conservation, soil fertility and farm income

Transcription

1 Systematic design and evaluation of crop rotations enhancing soil conservation, soil fertility and farm income Dr. Santiago Dogliotti Attached Professor Plant Production Department FACULTY OF AGRONOMY UNIVERSITY OF THE REPUBLIC URUGUAY FACULTAD DE AGRONOMIA

2 Layout of the lecture Introduction Impact of crop rotation on crop yields and soil fertility Design criteria Design tools Prototyping ROTAT Farm Steps Evaluation criteria and evaluation tools

3 A crop rotation is a sequence of crops grown in succession on a particular field Block 1b Bl 2a Bl 2a Block 5b Bl 5a Bl 3a Bl 4a Block 4b Block 6b Block 3b Block 7b Block 2b Bl 1a Bl 6a Bl 4a Bl 4a

4 Rotation effects on farm systems results Physical, chemical and biological soil fertility Crop yields Labor and inputs requirements = production costs Temporal distribution of the demand of labor and other resources, and cash flow

5 Rotation effect on potato yield (Scholte, 1989) Rotation Potato monocropping Potato yield (g/m2) % of stems infested with V. daheliae 99 c 49 a Maize - Potato 131 b 39 b Sugar beet - Potato 118 bc 50 a Maize - Sugar beet - Barley - Barley - Potato 152 a 21 c

6 Rotation effect on wheat yield (Berzsenyi et al., 2000) Wheat Yield (Mg/ha) Rendimiento (t ha -1 ) Monocropping monocultivo 22 Wheat-2 trigo - 2 Maize maíz 5 trigo Wheat-3-3 alfalfa Alfalfa 2 Wheat-3 2 trigo - Alfalfa 3 trigo Wheat - maíz - Maize - alfalfa -3 Maize - 3 maíz cebada Barley - arveja Peas

7 Effect of crop rotation on weeds population (Covarelli y Tei, 1988) Rotation Maize monocropping Number of weed seeds per m2 with weeding without weeding Number of weeds per m Maize - Wheat

8 Effect of crop rotation and cover crops on soil erosion and soil organic matter balance Traditional soil management Including Cover Crops Rotation Estimated Erosion (Mg/ ha yr) Soil Organic Matter balance (kg/ ha yr) Estimated Erosion (Mg/ ha yr) Soil Organic Matter balance (kg/ ha yr) 4 years Grass&Clover pasture - Onion - Sweet Potato - Sweet Maize - Onion (8 years rotation) 4 years Grass&Clover pasture - Onion - Sweet Potato - Sweet Pepper - Onion (8 years rotation) Onion - Autumn Potato - Sweet Maize - Sweet Potato - Sweet Maize (4 years rotation) Onion - Sweet Potato - Sweet Pepper - Sweet Maize (4 years rotation) Soil erosion estimated using RUSLE (Renard et al., 1997) and Soil Organic Matter balance estimated using ROTSOM (Dogliotti et al., 2004)

9 Effects of cover crops as inter-crop activity in crop rotations (Scholberg et al., in press) Process Primary effects Secondary effects Biomass production Food, fuel, forage (+) Soil amendment (+) Mulch layer (+) SOM (+) Carbon sequestration (+) Production costs (+/-) Canopy functions Nutrient storage Soil cover Soil nutrient supply (+) Weed suppression (+) Wind/water erosion (-) Runoff (-) Soil temperature (-) Soil moisture (+) Crop production (+) Nutrient leaching (-) Resource depletion (-) SOM (+) Crop water use effic. (+) Crop production (+) Sediment losses (-) Nutrient leaching (-) Cover crops Ecological functions Biodiversity (+) Habitat (+) Pest dispersal (-) Beneficials (+) Pests (-/+) Crop production (+/-) Soil/nutrient retention Wind/water erosion (-) Nutrient retention(+) SOM (+) Crop production (+) Environm. impacts (-) Root functions Root growth & exudates Root symbiosis Water infiltration (+) Water retention (+) Soil compaction (-) Runoff (-) Nutrient availability (+) Weed suppression (+) Nitrogen fixation (+) Mycorrhizal symbiosis(+) SOM (+) Crop production (+) Flooding (-) Groundwater recharge (+) Environm. impacts (-) Nutrient imbalance (-) SOM (+) Crop production (+)

10 Designing a crop rotation Which are the main characteristics that define a crop rotation? Crop species and families Frequency of each crop and crop family Sequences of crops Rotation length (time to complete a cycle)

11 Designing a crop rotation 1. Selection of crops Profitability, market, constraints related to farm resource availability Soil quality, water demand and climate requirements of crops Ensure variability in: Botanical families Harvested organ Soil cover Residue/yield ratio Growth period

12 Designing a crop rotation 2. Crop sequences (Vereijken et al., 1997) Never schedule successions of the same species or the same family or crops sensitive to a soil borne disease relevant in the region. After a crop with a negative effect on soil fertility schedule a crop with positive effect: soil cover, rooting system, organic resiudes, harvested organ, N left. Take into account harvest and sowing periods of each crop including enough time for appropriate soil tillage.

13 Designing a crop rotation 3. Crop frequency Estimated effect of crop frequency in the rotation on yield reduction from maximum yield (Molendijk y Mulder 1996). Crop Diseases Frequency in the rotation 1:2 1:3 1:4 1:5 1:6 1:7 Potato Globodera Verticillum Rhizotocnia Rhizomanie Onion and Ditylenchus Garlic Scl. Cepivorum Fusarium Maize Ditylenchus Wheat

14 Designing a crop rotation 4. Rotation Length or duration (years) Block 1b Bl 2a Bl 2a Block 5b Bl 5a Bl 3a Bl 4a Block 4b Block 6b Block 3b Block 7b Block 2b Bl 1a Bl 6a Bl 4a Bl 4a Rotation Irrigated Beans Leek WCC Table tomato WCC Sm Squash WCC Sw Maize Leek Ind Tomato WCC Sw Maize Length (yr) WCC 6 Rainfed Onion WCC Squash WCC Maize 7 4 years Grass clover pasture

15 Inter-crop activities : Aims Reduce soil erosion Increase soil organic matter content Reduce nutrient losses Improve soil structure Reduce weed seed bank Reduce the incidence of soil borne diseases

16 Tools to aid crop rotation design Prototyping (Vereijken et al, 1997) ROTAT FarmSTEPS

17 Evaluation of a crop rotation in prototyping approach (After Vereijken et al., 1997) Crop Soil cover Effects on soil fertility Effect of Compactation roots on due to tillage soil and harvest structure Organic Matter in residues Letuce Cabbage, Cawliflower Peas Carrots 2 a Onion Garlic Potato 2 a Tomato (table) Tomato (industry) Sweet pepper Sweet potato Squash Water melon Sweet maize Wheat Winter green manure Summer green manure G&L pasture Crop cover: No cover in autumn or winter = 0 No cover in spring or summer = 1 Partial cover in autumn or winter = 2 Partial cover in spring or summer = 3 Good cover = 4 Very good cover = 5 Organic matter input: <1000 kg MS/año = kg MS/año = kg MS/año = kg MS/año = kg MS/año = 4 >4000 kg MS/año = 5

18 Water balance at crop or crop rotation level Yield Reduction Factors Cropping frequency (single crop, groups of crops) Inter-crop management and crop-crop successions Production techniques such as: irrigation, crop protection, mechanization Quantification Field level RUSLE for crop rotations ROTEROSION Long-term fate of soil organic matter ROTSOM N P K balance Crop list Rules and filters ROTAT ROTYIELD Production Activities files Classified by soil type and management type with the yield of each crop in the rotation EEP - calculator Fodder calculator: energy, protein and qm Labor distribution calculator: half month periods Potential Crop Yields Gross and Net margin, capital requirements at field level Data handling program Crop Growth Simulation models or experimental yields DATABASE Software to aid design and evaluation of rotations, explorative approach (Dogliotti, 2003) Farm Scale SmartFarmer Farming systems design program (MILP)

19 Design and evaluation results Gross margin (US$ ha -1 ) a Labor (h ha -1 ) Soil erosion (Mg ha -1 ) b Labor (h ha -1 ) N surplus (kg ha -1 ) c Labor (h ha -1 ) EEP soil (kg-days) d Labor (h ha -1 ) SOM rate (kg ha -1 ) e Labor (h ha -1 ) Gross margin, soil erosion, N surplus, EEP-soil and rate of change of SOM as a function of the labour requirement per ha of production activities designed for high mechanisation level (Dogliotti et al., 2004)

20 The Farm STEPS approach 1. The crop plan: Based on the current crop and animal activities of the farm and only few new activities, it optimizes family income subject to constraints related to resource availability and agronomic rules 2. The cropping plan: Based on the history and eligibility of each field, the crop plan and agronomic rules, it allocates crop sequences to fields to produce a land use plan for the next few years. 3. Ex-ante evaluation of the plan: Based on technical coefficients and semi-quantitative indicators it evaluates the economic and environmental results of the cropping plan