Soil Health Presentation | Mahlathini Development Foundation

Learning Conservation Agriculture the Innovation Systems way

Grain-SA Smallholder Farmer Innovation Programme

Erna Kruger, Ngcobo P, Dlamini M and Smith H

CA-Farmer Innovation Programme

Key objectives and activities

Farmer-centred

Innovation

System

Awareness raising and

Access to Information

Incentives and

Market Based

Mechanisms

On-farm,

farmer-led

Research

Education

and Training

Farmers days,

symposiums, cross

visits, conferences,

popular articles

Subsidies, Village

Saving and Loan

Associations, farmer

centres, group based

access to equipment

and infrastructure

Farmer experimentation;

intercropping, crop

rotation, cover crops,

livestock integration.

Learning groups;

practical

demonstrations,

workshops, field

assessments

Stakeholder interaction,

partnerships, horizontal

and vertical scaling

CA Farmer led Trial summaries

Midlands

Bergville

EC, SKZN

Season

2017 2013

2014

2015 20162017

2013

2014

2015

2016

2017

No of villages

639 11 1718 410 88 13

No of trial participants

4228837321225923

43 5493

Area planted (trials)

-ha 1,362,87,2 5,913,517,4

0,36

0,3

0,37

1,18

3,58

Average yield maize (t/ha)

2,043,74 3,634,125,035,7

0,95

0,7

1,37

2,52

2,17

Min and max yield maize

(t/ha)

0,4-7,12-4,3 1-

6,7

0,6-7,4

0,3

11,7

0,5

12,2

0,3

1,7

0,3

1,8

0,5

4,4

1,1

5,2

0,2

6,7

Average yield beans (t/ha)

0,621,24 0,260,791,051,22

1,26

0,34

0,69

1,28

0,35

Trialsummaries over 5 seasons; Bergville,SKZN and EC

•For CA plots the pH is higher

on average and acid

saturation lower than on

control plots

•The required P has reduced

on CA plots

•And % Org C and % N

increased significantly

compared to control plots

•Savings of around R400/ha

made on inorganic N in

three seasons

•C:N ratios in the soil

decrease over time for the

CA plots

•Soil health scores are higher

for CA plots than control

plots

The CA system and effect on soil fertility and soil

health

Intercropping with

legumes (beans and

cowpeas) and use

of cover crops

increase soil fertility

and soil health

FASTER than

monocropping

Increased %

Organic C and %

N under CA

•Visual and quantitative indicators

•Visual Soil Assessments: soil cover, soil

structure, run-off, crusting,

earthworms, root size, soil porosity,

soil texture

•Measurements: infiltration, run-off

plots, weather stations

•Soil health analysis

Soil health; methods

•WEOC –sugars from root exudates,

plus organic matter degradation

•CO2–microbial activity/respiration

•WEON –Atmospheric N2sequestration

from free living N fixers, plus SOM

degradation

•C/N –Balance between WEOC and

WEON

•MAC% - efficiency of cycling of WEOC

(WEOC/CO2-C)

Soil health(SH) scoresCO2/10+WEOC/50

+WEON/10 =SH

score

Joining soil science and

ecology into a new

science of soil health

•Developed by Rick Haney –to

accommodate for and include the

organic fractions of nutrients in soil

sample analysis

•Recognising that soil health is a

dynamic process of cycling of nutrients,

microbial activity and degradation of

organic matter

•And the plant roots are active

participants in the cycling providing

carbonsugars as root exudates to

supply microbes with food

•C:N ratio is determined by soil chemical

properties and micro organisms present in

the soil.

•The lower this ratio is, the more organisms

are active and the more available the food is

to the plants. Good C:N ratios for plant

growth are <15:1.

•You can have a low or optimum C:N

(WEOC/WEON) within a range of values of

available organic carbon in the soil. (WEOC)

•If this value is low, it will reflect in the C02

evolution, which will also be low. So less

organic carbon means less respiration from

microorganisms, but again this relationship is

unlikely to be linear.

•The Microbially Active Carbon (MAC = WEOC

/ ppm CO2) content is an expression of this

relationship. If the percentage MAC is low, it

means that nutrient cycling will also be low.

One needs a %MAC of at least 20% for

efficient nutrient cycling.

•The SH score ranges between 0-50. the scale

is generally 0-3; 3-7; 7-15; 15-25; 25-50

Test results

ppmCO2-C

N-Mineralisation Potential

Biomass

>100

High-N potential soil. Likely

sufficient N for most crops

Soil very well supplied with organic

matter. Biomass>2500ppm

61-100

Moderately-high. This soil has

limited need for supplemental N

Ideal state of biological activity and

adequate organic matter

31-60

Moderate. Supplemental N

required

Requires new applications of stable

organic matter. Biomass<1,200ppm

6-30

Moderate-low. Will not provide

sufficient N for most crops

Low in organic structure and microbial

activity. Biomass<500ppm

0-5

Little biological activity; requires

significant fertilization

Very inactive soil. Biomass<100ppm.

Consider long-term care

What the values meanCONVENTIONAL SYSTEM: Mostly

decomposerfungi –small hyphal

networks, NB forsoil fertility, minor

role in carbon storage

CA SYTEM: Mostly Mycorrhizal fungi

–large hyphal networks, major role

in carbon storage

Mycorrhizal fungi get their

energy in a liquid form, as soluble

carbon directly from actively

growing plants. They access and

transport water- plus nutrients

such as phosphorus, nitrogen and

zinc - in exchange for carbon from

plants.

Soluble carbon is also channelled

into soil aggregates via the

hyphae of mycorrhizal fungi and

can undergo humification, a

process in which simple sugars

are made up into highly complex

carbon polymers.

Below: Mycorrhizal fungi grow very closely

associated with plant roots and create

networks of filaments (hyphae) within the soil)

Reserve Organic, 0

Release from Orga,

19.40

NO3, 1.10

NH4, 10.40

Total Inorganic, 11.5

Distribution of the Nitrogen components ppm

Reserve Organic, 7.4

Release from Orga,

1.00

NO3, 83.20

NH4, 2.80

Total Inorganic, 86

Distribution of the Nitrogen components ppm

BIOLOGICAL ANALYSES

Sample #

SOLVITA

CO2 Burst

WATER EXTRACT

C/N

Soil

Health

Calculatio

n (Index)

Commen

CO2 -

ppm C

Organic C

ppm C

Organic N

ppm N

ENZV 206.1379 19.419.5 24.2

Excellent

BIOLOGICAL ANALYSES

Sample #

SOLVITA

CO2 Burst

WATER EXTRACT

C/N

Soil

Health

Calculatio

n (Index)

Commen

CO2 -

ppm C

Organic C

ppm C

Organic N

ppm N

7.1 129 8.415.4 2.6

Soil Organic Matter

% 6.2

Microbial Active C (MAC)

%54.4

Soil Organic Matter

% 1.3

Microbial Active C (MAC)

%5.5

Comparing the nitrogen profile of natural “veld” with an intensively chemically farmed plot.

Comparing the nitrogen profile of natural “veld” with CA diverse cropped plot; Bergville, 2016/17.

BIOLOGICAL ANALYSES

Sample #

SOLVITA

CO2 Burst

WATER EXTRACT

C/N

Soil

Health

Calculatio

n (Index)

Commen

CO2 -

ppm C

Organic C

ppm C

Organic N

ppm N

EPHV 81,6326 18,417,716,5

Excellent

Reserve Organic, 0

Release from

Orga, 18.40

NO3, 0.30

NH4, 2.70

Total Inorganic, 3

Distribution of the Nitrogen components ppm:

Veld (P Hlongwane)

Soil Organic Matter

% 4

Microbial Active C (MAC)

%25

Reserve Organic,

4.2

Release from Orga,

21.20

NO3, 12.90

NH4, 4.30

Total Inorganic,

17.2

Distribution of the Nitrogen components ppm;

Maize + Cowpea intercrop (P Hlongwane)

BIOLOGICAL ANALYSES

Sample #

SOLVITA

CO2 Burst

WATER EXTRACT

C/N

Soil

Health

Calculatio

n (Index)

Commen

CO2 -

ppm C

Organic C

ppm C

Organic N

ppm N

EPHMCP

61,829625,4 11,7 14,6

Excellent

Soil Organic Matter

%3,3

Microbial Active C (MAC)

%20,9

Comparing the nitrogen profile of Mono-cropped Maizewith CA diversecropped plot; Bergville, 2016/17.

Reserve Organic,

4.2

Release from Orga,

21.20

NO3, 12.90

NH4, 4.30

Total Inorganic,

17.2

Distribution of the Nitrogen components ppm;

Maize + Cowpea intercrop (P Hlongwane)

BIOLOGICAL ANALYSES

Sample #

SOLVITA

CO2 Burst

WATER EXTRACT

C/N

Soil

Health

Calculatio

n (Index)

Commen

CO2 -

ppm C

Organic C

ppm C

Organic N

ppm N

EPHMCP

61,8296 25,411,714,6

Excellent

Soil Organic Matter

%3,3

Microbial Active C (MAC)

%20,9

Reserve Organic,

1.5

Release from

Orga, 21.70 NO3, 16.10

NH4, 2.30

Total Inorganic,

18.4

Distribution of the Nitrogen components ppm;

CA Maize control (P Hlongwane)

BIOLOGICAL ANALYSES

Sample #

SOLVITA

CO2 Burst

WATER EXTRACT

C/N

Soil

Health

Calculatio

n (Index)

Comme

CO2 -

ppm C

Organic C

ppm C

Organic N

ppm N

EPHC 59,6254 23,210,913,4

Excellent

Soil Organic Matter

% 3

Microbial Active C (MAC)

%23,5

•4-5 years: Reduced need for herbicide -no spraying on trial

plots this season

•Increased organic matter, reduced fertilizer requirements -

No basal fertilizer applied- only top dressing

•Reduced runoff

•Increased yields and diversity

Bergville: Case studyMphumelele Hlongwane- Ezibomvini

t/ha

2016

2017

Maize (Control)

-CA

7,8

9,7

Maize Trial CA

- combined

6,93

8,3

Beans

0,25

1,81

Sunflower

0,3

0,8

•EXPERIMENTS: Inter- cropping, crop

rotation, legumes, SCC, WCC

•Runoff plots: CA (1,1mm/event) vs

Conventional control (3,1mm/event)

•Infiltration: CA (247mm/hr) vs Control

(50mm/hr)

•Soil health 2016, 2017:

•Build-up of organic soil carbon and nitrogen in

the trial, with more microbially available carbon

and thus a much higher soil health score.

•Lower C:N ratios in CA plots (CCs and legumes

•AGGREGATE STABILITY: CA (43%-55%) CA

Control (33%) -higher aggregate stability for

the plots with crop diversification- highest for

inclusion of SCC mixes andLab-Lab

•% OM: CA average (3 ,47%), Veld Baseline

(2,5%) –accumulation of organic matter in CA

plots- now higher than veld baseline benchmark

(10)

M + B

(5)

Control plot

(8)

M + B

(6)

M +LL

(3) M + SCC

+WCC

Contro

l plot

(9)

M + CP

(7)

M + CP

(4)

M + B

(2)Sunn

hemp,

millet and

sunflower

(1)

M + B

Legend: M –Maize; B –Beans; CP –Cowpea; LL –Lab Lab; SCC –summer cover crop WCC –

winter cover crop

Bergville: Case study-continued

4 Participants over 3 seasons-

crop diversity (intercropping and

cover crops) and crop rotation to

a lesser extent. AVERAGE FOR ALL

TRIAL PLOTS SHOWN

•The Organic Carbon content

has INCREASED for all 4

participants

•The Organic Nitrogen content

has INCREASED for all 4

participants

•C:N ratios have decreased for

Phumelele Hlongwane only –as

she has most coherently

implemented the diverse

cropping and crop rotation

process (including legumes).

•Soil health scores have

increased significantly between

2016 to 2017

Soil health Test results: 3 seasons 2015-2017

Average values of

different cropping

options across three

seasons for 9

participants

•If one compares

single crops (maize

only) to the mixed

crop options

(intercrops and cover

crops) then

-Organic Carbon and

Organic Nitrogen are

HIGHER

-C:N ratios are LOWER

-Soil health scores are

HIGHER

for all the mixed

cropping options - except

for maize and bean

intercrop option

Soil health Test results: Different Cropping options 2015-2017

•3-4 years: Animal drawn traction –larger plot –very sandy

, extremely low organic matter (0,6%).

•Germination, growth and yields have increased –albeit

slowly; Maize 0,78-1,4t/ha, beans stable at 0,16t/ha

•Increased diversity –legumes and cover crops

•Reduced run-off and erosion

•Reduced weeds

•Increased soil health

Eastern Cape: Matatiele Case study Tsoloane Mapheele–Khutsong- Matatiele

•EXPERIMENTS: single crops, Inter-cropping,

legumes, SCC, WCC, Lucerne

•Soil health 2016-2017:

•Reduction in C:N ratio and increase in organic N in his intercropped

trial plots as compared to his Maize only control plot, indicating an

increase in soil health.

•Soil health scores for the trial plots are higher than the control

plots, but still below average given the extremely sandy and

infertile soils he is working on.

Case study continued

Cont (M)TrialveldTrial

2016 2017

Average of %OM0.6 0.710.6

Average of CO2 - C, ppm C16.8 14.6 19.2 14.6

Average of Organic C ppm C118 116 14573

Average of Organic N ppm N7.58.5 12.4 12.1

Average of C:N ratio15.7 13.6 11.76.0

Average of Soil health Calculation3.0 3.1 4.3 4.0

100

120

140

160

Indicators

Soil Health Indicators Tsoalone Mapheele; 2016-2017

•In Matatiele (EC) soils are generally poor and veld

benchmark values tend to be lower than the CA trial

values

•The increasein available nitrogen (2016-2017)

amounts to an average Rand value of about R150

more than the veld samples. This indicates a

potential saving on bought fertilizer of around 14%

•In addition Immediate release N has increased

substantially over the veld bench mark values and is

higher for 2017; indicating a cropping pattern under

the CA trialsthat builds organic nitrogen in the soil.

•In Bergville the picture is a bit different. Soils are

good and veld benchmarks are high –excellent

•Here only the trials in Ezibomvini have higher total

Nitrogen amounts than the veld. The Rand value of

available organic N here is R64 more than the veld

benchmark, indicating a potential saving on bought

fertilizer of around 6%.

Nutrient cycling- Nitrogen; Comparison EC and Bgvl

2016 2017 2016 2016 2017 2016 2016 2017 2016

Trial Veld Trial Veld Trial Veld

KhutsongNkau Sehutlong

Average of N(kg/ha) Total21584151 308 422 280 325 378 280

Average of R value of Org

N103 243 175 263 353 129 162 24384

Average of N Immediate

release 622 10 16 31810 225

100

150

200

250

300

350

400

450

Matatiele; Nitrogen 2016- 2017

•Intercropping and use of

cover crops is very

important for building soil

fertility and soil health

•Crop rotation aids in

stabilising high soil health

scores over time

•The more crops you use

and rotate the better

•Having legumes in the mix

speeds up the process

Soil Health Summary

Crop diversity is

crucial

Crop rotation in

combination with

crop diversity

supports this

process

Lab-Lab and SCC

provide for very

high organic C

and N values

Lower C:N ratios are

found in crop mixes

that contain legumes

–cowpeas, Lab-Lab