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Systematic design and evaluation of crop rotations enhancing soil conservation, soil fertility and farm income
FACULTAD DE AGRONOMIA
Dr. Santiago DogliottiAttached Professor Plant Production Department
FACULTY OF AGRONOMY – UNIVERSITY OF THE REPUBLICURUGUAY
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
“A crop rotation is a sequence of crops grown in succession on a particular field”
Block 1b
Block 5b
Block 2b Block 3b Block 4b Block 6b Block 7b
Bl 2a Bl 2a
Bl 1a
Bl 4a
Bl 4a Bl 4a
Bl 3a Bl 5a
Bl 6a
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
Rotation effect on potato yield (Scholte, 1989)
RotationPotato yield
(g/m2)
% of stems infested with V. daheliae
Potato monocropping
99 c 49 a
Maize - Potato 131 b 39 b
Sugar beet - Potato 118 bc 50 a
Maize - Sugar beet - Barley - Barley -
Potato152 a 21 c
Rotation effect on wheat yield (Berzsenyi et al., 2000)
0
1
2
3
4
5
6
monocultivo 2 trigo - 2 maíz 5 trigo - 3 alfalfa 2 trigo - 3alfalfa - 3 maíz
trigo - maíz -cebada - arveja
Ren
dim
ient
o (t
ha-1
)
WheatY
ield(M
g/ha)
Monocropping 2 Wheat-2 Maize 5 Wheat-3 Alfalfa 2 Wheat-3 Alfalfa Wheat - Maize-3 Maize Barley - Peas
Effect of crop rotation on weeds population (Covarelli y Tei, 1988)
with weeding
without weeding
Maize monocropping
24500 55800 422
Maize - Wheat 18920 19300 161
Number of weed seeds per m2
RotationNumber of
weeds per m2
Effect of crop rotation and cover crops onsoil erosion and soil organic matterbalance
RotationEstimated
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)
6.8 + 22 6 + 71
4 years Grass&Clover pasture - Onion - Sweet Potato - Sweet Pepper - Onion (8 years rotation)
9.0 + 8 6.5 + 61
Onion - Autumn Potato - Sweet Maize - Sweet Potato - Sweet Maize (4 years rotation)
13.5 - 152 7.6 - 8
Onion - Sweet Potato - Sweet Pepper - Sweet Maize (4 years rotation)
15.5 - 173 11.6 - 24
Traditional soil management Including Cover Crops
Soil erosion estimated using RUSLE (Renard et al., 1997) and Soil Organic Matter balance estimated using ROTSOM (Dogliotti et al., 2004)
Effects of cover crops as inter-crop
activity in crop rotations(Scholberg et al., in press)
Process
Cover crops
Canopy functions
Root functions
Soil cover
Primary effects
Biomass production
Nutrient storage
Soil/nutrient retention
Root symbiosis
Root growth & exudates
Ecological functions
Secondary effects
• Food, fuel, forage (+)• Soil amendment (+)• Mulch layer (+)
• Crop production (+) • Nutrient leaching (-)• Resource depletion (-)
• SOM (+)• Carbon sequestration (+)• Production costs (+/-)
• Weed suppression (+)• Wind/water erosion (-)• Runoff (-)• Soil temperature (-)• Soil moisture (+)
• Soil nutrient supply (+)
• SOM (+)• Crop water use effic. (+) • Crop production (+)• Sediment losses (-)• Nutrient leaching (-)
• Biodiversity (+)• Habitat (+) • Pest dispersal (-)
• Beneficials (+)• Pests (-/+)• Crop production (+/-)
• Wind/water erosion (-)• Nutrient retention(+)
• SOM (+) • Crop production (+) • Environm. impacts (-)
• 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 (+)
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)
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
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.
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).
Designing a crop rotation
1:2 1:3 1:4 1:5 1:6 1:7
Potato Globodera 0.25 0.5 0.75 0.9 1 1
Verticillum 0.85 0.9 0.94 0.97 1 1
Rhizotocnia 0.9 0.93 0.95 0.98 1 1
Rhizomanie 0.9 0.92 0.93 0.94 0.95 1
Onion and Ditylenchus 0.5 0.75 0.85 0.9 1 1Garlic Scl. Cepivorum 0.5 0.6 0.65 0.7 0.75 1
Fusarium 0.2 0.4 0.6 0.7 0.75 1
Maize Ditylenchus 0.75 0.9 1 1 1 1Wheat 0.75 0.9 1 1 1 1
Frequency in the rotationCrop Diseases
Designing a crop rotation4. Rotation Length or duration (years)
Block 1b
Block 5b
Block 2b Block 3b Block 4b Block 6b Block 7b
Bl 2a Bl 2a
Bl 1a
Bl 4a
Bl 4a Bl 4a
Bl 3a Bl 5a
Bl 6a
RotationLength
(yr)
IrrigatedBeans Leek
WCCTable
tomatoWCC
Sm Squash
WCCSw
MaizeLeek
Ind Tomato
WCCSw
MaizeWCC 6
Rainfed Onion WCC Squash WCC Maize 74 years Grass clover pasture
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
Tools to aid crop rotation design
� Prototyping (Vereijken et al, 1997)
� ROTAT
� FarmSTEPS
Evaluation of a crop rotation in prototyping approach (After Vereijken et al., 1997)
Crop cover:No cover in autumn or winter = 0No cover in spring or summer = 1Partial cover in autumn or winter = 2Partial cover in spring or summer = 3Good cover = 4Very good cover = 5
Organic matter input:<1000 kg MS/año = 01000-2000 kg MS/año = 12000-3000 kg MS/año = 22000-3000 kg MS/año = 33000-4000 kg MS/año = 4>4000 kg MS/año = 5
Crop Soil coverCompactation due to tillage and harvest
Effect of roots on
soil structure
Organic Matter in residues
Letuce 0 2 0 0Cabbage,
Cawliflower2 2 1 0
Peas 1 2 0 0Carrots 2 a 3 0 0 0Onion 0 1 0 0Garlic 0 1 0 0Potato 2 a 3 0 0 0
Tomato (table) 2 2 1 0Tomato (industry) 3 2 1 1
Sweet pepper 2 2 1 1Sweet potato 4 0 1 1
Squash 3 2 1 1Water melon 2 2 1 0Sweet maize 3 2 2 2
Wheat 4 3 4 2Winter green
manure4 3 4 4
Summer green manure
3 3 4 4
G&L pasture 5 4 4 5
Effects on soil fertility
ROTAT♦Crop list♦Rules and filters
ROTYIELD
Potential Crop Yields
Crop Growth Simulation models or experimental yields
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
Production Activities filesClassified by soil type and management type with the yield of each crop in the rotation
DATABASE
Quantification Field level
RUSLE for crop rotationsROTEROSION
Long-term fate of soil organic matter
ROTSOM
N – P – K balance
EEP - calculator
Fodder calculator: energy, protein and qm
Labor distribution calculator: half month periods
Data handling program
SmartFarmerFarming systems
design program (MILP)
Farm Scale
Gross and Net margin, capital requirements at field level
Water balance at crop or crop rotation level
Software to aid design and evaluation ofrotations, explorative approach (Dogliotti, 2003)
Design and evaluation results
a
-500
0
500
1000
1500
2000
2500
0 500 1000 1500
Labor (h ha-1)
Gro
ss
mar
gin
(U
S$
ha-1)
b
0
2
4
6
8
10
1214
16
18
0 500 1000 1500Labor (h ha-1)
Soi
l ero
sion
(Mg
ha
-1)
c
0
20
40
60
80
100
120
140
0 500 1000 1500
Labor (h ha-1)
N s
urpl
us (k
g h
a-1
)
d
0
50
100
150
200
250
300
350
400
450
0 500 1000 1500Labor (h ha-1)
EEP
soi
l (kg
-da
ys)
e
-400
-300
-200-100
0
100
200
300400
500
600
0 500 1000 1500
Labor (h ha-1)S
OM
rat
e (k
g 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 productionactivities designed for high mechanisation level (Dogliotti et al., 2004)
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