1. Nutrient Balance and Soil Quality
in Agroecosystems
Fernando O. García
fgarcia1957@gmail.com
@garciaf_nutri
Concepción, 21 March 2023

2. Why nutrient balance and
soil quality/health?
• Soils are involved in most of SDGs
• One Health: soil + plants + animals +
humans + environment (Lal, 2021)
• Soils and human health: food
production, C sequestration,
detoxification, water and nutrient
retention, biodiversity (Brevik et al.,
2020).

3. Outline
•Introduction: Some definitions and scope
•Field crop systems of South America
•Soil quality/health status, threats and challenges
•Nutrient balances at different countries/regions
•Management to maintain/improve soil health and
nutrient balances

4. What is Soil Quality/Health?
“the ability of the soil to sustain
the productivity, diversity, and
environmental services of
terrestrial ecosystems”
Intergovernmental Technical Panel on Soils
(ITPS, 2020)

5. Soil fertility
• … is the ability of a soil to sustain the
growth of plants by providing essential
nutrients and favorable chemical, physical
and biological characteristics as a habitat
for their growth (FAO, 2019)
FAO (2019,2022)

6. Indicators of nutrient use efficiency
(Dobermann, 2007; Norton et al., 2015)
Indice Estimation
Typical levels for N
(maize or wheat)
Agronomic efficiency (AE) (Y-Y0)/F
10-30
kg grain/kg nutrient
Recovery efficiency (RE) (U-U0)/F
30-50%
∆ kg nutrient uptake/kg applied nutrient
Partial Productivity Factor
(PPF)
Y/F
40-80
kg grain/kg nutrient
Partial Nutrient Balance
(PNB)
R/F
>1.00 = Deficit
<1.00 = Excess
kg grain nutrient /kg nutrient
Y= yield, F = fertilization, R = removal, U= uptake
scale and objective use of the index … always an output/input ratio

7. Impacts
of
nutrient
balances
FAO (2022)

8. Pampas
Cerrados
Amazonas
South central
Brazil
Great Chaco
Central valleys
of Chile
WRB, FAO (2014)
Andes
(highlands
and valleys)
Volcanic soils of
southern Chile
Main soil health challenges
• Wind and water erosion
• Soil organic matter (SOM)
depletion
• Nutrient losses
• Soil compaction
• Salinization
• Biodiversity losses
• Contamination
South America soils and agroecosystems
Erosion - Ecuador
M. Ramos
Erosion
Alto Paraná, Paraguay
K. Moriya, 2011
Uruguay
Argentina
Río de la
Plata
Océano
Atlántico
Eutrophication
Rio de la Plata
L. Carrasco, 2015
Expansion into fragile ecosystems
Carmen de Patagones, Argentina
D. Iurman, INTA Ascasubi, 2009
Expansion into fragile ecosystems
“Chaqueos” at Bolivia
F. Garcia
Salinization
Santa Cruz, Bolivia
M. S. Viera, 2014
Compaction
G. Cordone y G. Gerster
INTA Casilda y Roldán, 2005

9. Soil nutrient budgets per cropland area, 2018
FAOSTAT Soil nutrient budget, 2021

10. 0.0
1.0
2.0
3.0
4.0
5.0
Argentina Bolivia Brasil Paraguay Uruguay Australia Canada EE.UU.
Relación
Remoción/Aplicación
(BPN)
N P K
Removal to Application Ratio (PNB) for N, P, and K at Argentina, Bolivia,
Brazil, Paraguay and Uruguay, and comparison with other countries
Elaborated from Fertilizar AC and Minagro (2017-19), FAOSTAT, ANAPO, da Cunha et al. (2018), Causarano (2017),
update 2020 from Mancassola and Casanova (2015), Edis et al. (2012), NuGIS-IPNI (2012)
Removal
to
Application
Ratio
(PNB)
Application > Removal
Removal > Application
US

11. Adapted from EU Nitrogen Expert Panel (2015)
NUE 90% = PPF 80 kg grain/kg N
Maximum excess 80 kg N
NUE 60% = PPF 50 kg grain/kg N
NUE 30% = PPF 25 kg grain/kg N
“Ideal”
Contamination risk
Soil degradation risk
… how are Nitrogen Use Efficiencies (NUE) in maize …
Partial Productivity Factor of N (PPF-N) = Yield / N rate
Argentina
Brasil
Bolivia
Paraguay
Uruguay
Chile
Perú
México
N rate (kg/ha)
Maize
yield
(kg/ha)
NUE30 NUE60 NUE90

12. Pillars of sustainable soil management for improved soil health
Rotations + No-tillage + Cover crops + Balanced nutrition
Studdert et al., 1997; Studdert and Echeverria, 2000; Ernst and Siri-Prieto, 2009; Novelli et al., 2013; Sá et al., 2014, 2017; Nunes
et al., 2020; Carvalho et al., 2021; Gabbarini et al., 2021; Nicoloso and Rice, 2021; Rui et al., 2022; Mikha and Marake, 2022;
Pires et al., 2023
Soil organic carbon as the comprehensive soil health/quality indicator
Rotations/cropping intensity
• Crop diversity
• Pasture/crop rotations
• Santa Fe system, agriculture/livestock integration
No-tillage
• Minimum disturbance
• Reduce erosion
• Soil C increases and stratification
• Improved soil microbial biomass and activity
Cover crops
• Root and microbial diversity
• Improved soil structure
• N fixation
• Reduce erosion
• Weed control
Balanced nutrition
• Improved yields
• Improved soil carbon
• Improved soil microbial biomass and activity

13. Rotations + Balanced nutrition
Long-term experiment at INIA La Estanzuela (Uruguay)
Agricultural diversification and intensification lead to 30% higher crop
yields and 19% greater SOC
Cont ag
Cont ag Fert
33% Ag 66% Past
Cont ag Cont ag
Fert
33% Ag
66% Past
Soil
Organic
Carbon
(g/kg)
Accumulated
grain
yield
(Mg/ha)
Grahmann et al., 2020

14. Sá, et al., Land Degradation and Development, 2015
Sequestered C = 0.423 + 0.165 C
R² = 0.83
p = 0.0006
0.0
0.5
1.0
1.5
2.0
2.5
3.0
3.5
0.0 2.0 4.0 6.0 8.0 10.0 12.0 14.0 16.0
Annual
C
gain
(Mg
ha
-1
)
Annual C input (Mg ha-1)
Carbon restoration by no-till cropping systems in oxisolls of Brazil
Sá et a. (2015)
Cropping intensity + No-tillage
Brachiaria and other cover crops
Santa Cruz, Bolivia
” … NT cropping systems with
high C input have a large
potential to
reverse the process of soil
degradation and SOC decline.”

15. Nutrition network CREA Southern Santa Fe (2000-19) – García et al. (2022, 2023)
Balanced NPS nutrition contributes 15% to 47% to
crop yields in the central Pampas of Argentina
Bulk density tend to decrease under
balanced NPS nutrition
Improving nutrient balances: Effects on yields and soil health in long-term experiments
41%
51%
29%
15%
40%
47%
27%
15%
9%
9%
14%
6%
10%
26%
12%
7%
25%
25%
6%
3%
Maize
Wheat
DC
Soybean
FS
Soybean
Relative response (%)
N P S NPS NPS+Micros
1
1.1
1.2
1.3
1.4
1.5
2003 2012 2021
Bulk
density
(g
cm
-3
)
Reference Check NPS
1
1.1
1.2
1.3
1.4
1.5
2003 2012 2021
Bulk
density
(g
cm
-3
)
Reference Check NPS
Balducchi - Teodelina, Santa Fe
La Blanca - A. Ledesma, Córdoba

16. Conceptual relationships between N fertilizer input and maize yield, residue production, and
residual soil inorganic N
Poffenbarger et al. (2017) - https://journals.plos.org/plosone/article?id=10.1371/journal.pone.0172293
Would balanced nutrition always improve yield and soil health/quality?
High nutrient use efficiency Low nutrient use efficiency
AONR = Agronomic Optimum Nitrogen Rate

17. Improving soil health through a systemic and integral
approach to soil fertility…
üDecoupling ag production from externalities
Adapted from Moraes Sá and Rice
Oats
Oats
Soybean Soybean
Wheat
Corn
Crop
Residues
Continuous
C Flux
Organic
compounds
MBC e MBN;
humic
compounds
Active Pool Slow
Pool Passive
Pool
Bulk Density;
SOC and N
pools
Soil carbon pool
C; DpH;
CTC; P e
K
physical, chemical and
biological properties
Intensification and Diversification
Soil
Organic
Carbon
Microbial
Activity
Nutrient
Cycling
Soil
Structure
Soil
Biodiversity
Water
Erosion
&
Availability
Gaseous
Emissions
Plant Growth
Yield
Environmental
Services
Sustainability
Rice (2018)

18. Conceptual model of Soil Quality Index (SQI) in BioAS
SQI
Fertbio
Soil organic matter
CEC
Acidity (H+Al, Al+3)
Supply of K, Ca, Mg,
cation saturation
β-Glicosidase
Arilsulfatase
Nutrient
cycling
Nutrient storage
Nutrient
supply
Biological SQI =
Chemical
SQI
Value from 0 to 1
P supply
I. C. Mendes et al., 2021

19. Thank you!
Fernando O. García
fgarcia1957@gmail.com
@garciaf_nutri