Polycropping

HAPPY CHRISTMAS EVERYONE! Hope everyone had a good time :) I sure did, spent some time admiring the natural wonders of Slovenia! Explains the hiatus for the past few weeks heh...

Anyway back to the topic!

I came across this rather interesting slide from a lecture by Plant Pathologist Dr Nelson (University of Hawaii) on "Poly- & Monocultures"

It shows the evolutionary pathway of  aspects of agriculture- most of which has been covered in my previous posts except: 3) Intercropping/Multicropping/Polycropping

The Green Revolution (i.e. Conventional Agriculture) resulted in widespread adoption of monocropping techniques.  As mentioned, the adoption of these techniques, while they seem to lead to short-term employment and profits, are unsustainable from an ecological point of view. In  contrast to monocropping is the method of polyculture (agroforestry is a form of it).

What is polyculture?

It is the planting of more than 1 species of crops which also involves the rotation of crops (and in some cases livestock) on a piece of land (UNESCO glossary)

What are the benefits of polyculture?

Here are 2 big benefits:

1. Higher Genetic Resilience to Epidemics

In fact, it has been observed that  certain diseases do not occur amongst plants such as the papaya until monocropping techniques were applied. There are two reasons for this:

• A lack of genetic diversity results in the wiping out of entire crops with a single pathogen
• Proximity of plant stands results in higher transmissions of pathogens

Such biological caveats play out clearly in economic and social consequences: In Hawaii, many lands were abandoned due to epidemics such as the papaya ringspot which caused the destruction of whole plantations. In contrast, typical polyculture (and in this case in the form of agroforestry- see my previous post for more on this) which consists of papaya being planted with other fruits result in lower pest pressure (Nelson, 2006). This has also been evident in eggplants which when grown together with buffelgrass produce over 100% yields compared to conventional treatments due to the lowered mite infestations and lower weed densities (Learyet al. 2006). 

2. Higher Yields

With more in-depth studies comparing mono VS polycropping in recent years, experts are now questioning the fact that in the longer term and taking a bigger-view of things (i.e. taking into account water-use, transport, fertilizer-use), polyculture is the more economically-viable form of agriculture (Roslin,2008) (and, yay!, this fulfils our principled approach of both caring for the environment and ensuring food security). For example, there is substantial evidence supporting this: intercropping in Africa resulted in lower interspecies competition and so higher yields (Harrison, 1987). In a long-term review of integrated croppings systems, Chavas et al. (2008) showed that rotational systems outperformed farms with conventional practices. 

3. Lower environmental costs (even environmental benefit)

In terms of how to replenish the soil,the use of practices such as living plant mulch by multiple-cropping creates  lots of benefits to the system (E.g. increasing yield 4-fold,  filtration, water-holding,erosion-resistance (Harrison, 1987)). Also, many of these systems use animal slurry which instead of becoming a form of waste that needs to be rid off (coupled with the possibility of polluting downstream ecosystems), it is now used as fertilizer without the problem of transportation (transporting manure the way we transport chemical fertilizer would be absolutely inefficient as i mentioned previously in this post). In fact, it has been shown that adjacent uncultivated land left untouched would render higher yields than if it were to be cultivated because of positive biodiversity effects of pollinators (Figure below). For example, canola yields are highest when 30% of the land is left uncultivated/left to go fallow- this goes against conventional thinking which assumes a direct correlation between land and yield (Moradin et al 2006).

But, how feasible is polyculture?

So it might be true that polyculture has proven itself to be ecologically superior. But are the societal conditions ready to make it happen?

I quote from an FAOpublication:

"It is now commonly argued that monocrop systems based on off-farm inputs cannot be sustained and that there should be a shift to low external input mixed farming systems which would be more appropriate for resource-poor farmers. While this is a laudable objective from both an ecological and an equity point of view, it is unrealistic for many situations at the present time from both economic and humanitarian standpoints because food availability would decline and food prices would rise"

Herein, there seems to be a conflict of interest. However, interestingly, the author of this publication argues that the "unrealistic" actually only refers to a lack of political will which is really just up to us to rectify. In essence, because of the efficiency of such systems, "food prices won’t rise" he argues.

And so, I would like to end this post with an example/case study which I am personally very inspired about. You might have heard of Joel Salatin's Polyface Farm.  It is probably quite justified to say that he is a master of polyculture and I respect his philosophy very much. Interestingly, Joel is strong organic-critic, in particular, industrial organic. I think anyone in this field should take consider this way of thinking because it works.  And looking at the results… my does it really work!

This video sums it up well (HIGHLY WORTH WATCHING!)

"40,000 lbs beef

30,000 lbs pork

10,000 broilers

1,200 turkeys

1,000 rabbits

35,000 doz. eggs

All Off 100 acres

and at the end of the year

there is more biodiversity, not less

there is more fertility, not less

there is more soil, not less.

The significance of this is that, it is NOT a zero-sum system!"

Here's how it looks like in real-life:

From another video interview, about how this might work, I glean several traits of his philosophy in showing that with the right implementation, polyculture isn't "unrealistic":

1. It is "profitable"
   This is really the primary concern of farmers' & feasibility in the modernized society. What is not profitable won't work in the real world. Through direct-marketing and word of mouth coupled to rewards, small farms practicing polyculture can survive.
2. It learns from nature's "healing relationships"Joel's polyfacefarm aims to understand the symbiosis between species, by "massaging close-relationships between animals". "I'm a grass farmer" says Joel- because grass is the mediator for building these healthy relationships.

3. It benefits "human health"A strong example would be that grass-fed beefs have consistently showed greater benefits in health compared to  grain-fed beef (Daley et al. 2010) 

4. It maximizes the appropriate use of science technology that lowers costsUnlike anti-technology methods (like some organic farms perhaps?), his farm uses state of the art technology but not those which are resource-intensive such as electric fences/paddock to herd up and section the area required for fertilization of animals.  Then, through understanding the lifecycle of pests and predators and timing the feeding cycles accordingly, another animal's waste becomes another's food i.e. no wastage. For example, chickens feed off the maggots in the cow dung while their faeces fertilizers the ground with more bio-available nutrients and ducks are fed during snail control (video below)

(If interested, here are videos of other farms applying similar philosophies to much success)

(Cute-factor alert! Seriously, look how happy the ducks are haha :p)

"Husband and wife team, farmers Mike Guebert and Linda Bangs live on 10 acres of land, raising and tending to a variety of livestock. Currently, they have 2 Jersey cows, and 40 goats that provide raw milk; about 250 laying chicken hens for eggs, and 800 chickens for (meat) broilers; and 5 turkeys: 4 hens, and one happy tom. Oh yes, and not to forget, 2 heritage breed pigs, and just the day before we arrived this spring (2012), they picked up 14 wiener pigs."- Video description

But how far can such individual case-studies go?

This is a very valid question to ask, and one which we probably don’t currently

have answers to. However, in his reasoning, Michael Pollen also holds the same respect I do for this method of farming, says this "Models are very important, we need good models. You can ask me if this farm can be scaled up… But the fact that it exists, I think can help us define what we mean by this word 'sustainable' "

Localized conditions would require tailoring of these methods and I doubt Joel would advocate wholesale adoptions of his methods worldwide. Also, this degree of understanding nuance in life-cycle coordination would require small-scale farms rather than large-scale mechanized ones without the ability to respond as quickly to variabilities of our environment. Perhaps then what is needed is a mindset change that small-farms can work and are not necessarily inferior in efficiency to large ones.

In conclusion...

I think what Joel Salatin has shown can be summed up in a sentence: Do to the environment what you would have it do to you. (slightly cheesy I know.. haha). It seems from the above that this way forward, you can't go very wrong… and in fact you can reap more rewards!