Thursday, 21 April 2016

How long does it take to improve soil ? - Polyculture Market Garden Study

One of the things I love most about the way we grow is how each year everything seems to improve -  richer biodiversity, more and tastier produce and healthier soils.

We've been monitoring what effect our cultivation practices have on the soil to see whether our observations are confirmed by testing. We take two soil samples from our gardens, one in March before fertilising and another in November after the last crops are harvested.

We started the market garden in March 2015.  The results below represent the first and second soil tests in the garden and results from samples taken in March of this year.

Soil Mineral Analysis and pH   


2015
MarchpH (KCI)N03NNH4NP205K20
5.6915.42.8916.313
NovemberpH (KCI)N03NNH4NP205K20
6.4416.24.4543.914.4
2016
Nitrogen mg/kgPotassium and Phosphorous mg/100g
MarchpH (KCI)N03NNH4NP205K20
6.654.435.798825.2







It's pleasing to see our market garden soils improving after the first year of cultivation and that's with taking out 358 kg of produce last year (see here for a summary of all results).

Also interesting to see is the reduction in plant available N (N03N) from Nov- March, probably due to high levels of carbon rich straw mulch left over after the growing season. The soil microbiota will be using the nitrogen to break down the high carbon straw.

Soil Health Visual Testing 


As well as the laboratory analysis of our soils we also take visual tests using a soil health test developed by farmers for farmers to track the development of soil health. These test show great improvements in the soil over a period of just 13 months.

 Polyculture Study team carrying out soil heath test in the market garden.

Soil Test Card comparison 2015 vs 2016 

2016TESTRESULTTEST SCORES 1 - 9
POOR 1 --------- 2 --------- 3FAIR 4 --------- 5 -------- 6GOOD 7 ---------- 8 --------- 912345Av
1.GROUND COVERLess than 50% ground cover [ground plants or mulch50% to 75% ground cover [ground plant or mulch]more than 75% ground cover [ground plant or mulch]999999
2.PENETROMETERWire probe will not penetrateWire probe penetrates with difficulty to less than 20 cmWire probe easily penetrates to 20 cm94,595,55,56.7
3.INFILTRATIONMore than 7 minutes3 to 7 minutesLess than 3 minutes999999
4. DIVERSITY OF MACROLIFEFewer than two types of soil animalsTwo to five types of soil animalsMore than five types of soil animals997998.6
5. ROOT DEVELOPMENTFew fine roots only found near the surfaceSome fine roots mostly near the surfaceMany fine roots throughout977887.9
6. SOIL STRUCTUREMostly in clods or with a surface crust, few crumbsSome clods but also many 10mm crumbsFriable, readily breaks into 10mm crumbs656465.4
7. AGGREGATE STABILITYAggregate broke apart in less than one minuteAggregate remained intact after one minuteAggregate remained intact after swirling
10cm depth898888.2
20 cm depthnot takennot takennot takennot takennot takennot taken
8. EARTHWORMS241954.1
Total58.9
2015TESTRESULTTEST SCORES 1 - 9
POOR 1 --------- 2 --------- 3FAIR 4 --------- 5 -------- 6GOOD 7 ---------- 8 --------- 912345Av
1.GROUND COVERLess than 50% ground cover [ground plants or mulch50% to 75% ground cover [ground plant or mulch]more than 75% ground cover [ground plant or mulch]867777
2.PENETROMETERWire probe will not penetrateWire probe penetrates with difficulty to less than 20 cmWire probe easily penetrates to 20 cm644334
3.INFILTRATIONMore than 7 minutes3 to 7 minutesLess than 3 minutes411111.6
4. DIVERSITY OF MACROLIFEFewer than two types of soil animalsTwo to five types of soil animalsMore than five types of soil animals111111
5. ROOT DEVELOPMENTFew fine roots only found near the surfaceSome fine roots mostly near the surfaceMany fine roots throughout466555.2
6. SOIL STRUCTUREMostly in clods or with a surface crust, few crumbsSome clods but also many 10mm crumbsFriable, readily breaks into 10mm crumbs546454.8
7. AGGREGATE STABILITYAggregate broke apart in less than one minuteAggregate remained intact after one minuteAggregate remained intact after swirling
10cm depth453785.4
20 cm depth778867.2
8. EARTHWORMS055333.2
Total39.4

See here for the results of our polyculture studies from 2014 - 2016

We offer a range of plants and seeds for permaculture and forest gardens from our plant nursery including a new range of fruit and nut cultivars well suited to natural gardens. Delivery to all over Europe available from Nov - March 



 Balkan Ecology Project Bio-Nursery 


References 

  1. This soil health card was developed as part of the Good Soil Project and the Good Worm Project, initiatives of Tuckombil Landcare Inc. in partnership with NSW DPI (then NSW Agriculture) and the Natural Heritage Trust. You can download the card here.
  2. Our samples our analysed by   The Ministry of Agriculture and Food 




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