Humble Designs- Southern Creek Flats

As a change of pace I decided to make this post focus on the design I am putting together for a section of the farm. I much prefer talking about results and experiences rather than plans. This space is on my creek flats where the soil is better quality and deeper than on the hills that cover the majority of the farm. The space is a section 80 m x 25 m (a half acre) that runs along the gully that overflows from some dams (in blue). High voltage power lines run across the lower section. The land is still gently sloping toward the gully, giving it a slight tilt toward the north-east. Given the decent soil here this is an ideal location for growing field crops. Its distance from the goat shed and size means I can’t expect this area to be supported by manure. The only input is planned to be charcoal from nearby woody waste, wood ash, silt from the gully and maybe a little urine.

Target area outlined in red. A similar space outlined in pink is just uphill to the south west. Goats currently graze west of the black outline electric fence. Blue indicates gully overflowing from dam in the north to creek in the south. Unmarked powerlines run across the southern corner. Current Tithonia hedges outlined in green

The space was originally part of a cow paddock and was grazed periodically. The area to the south west is separated by a barbed wire and electric fence (in black) and is now being used to graze the goats and they should be rotating through here for many years. The nearest section of goat paddock (outlined in pink) has similar soil, slope and aspect so could potentially be expanded onto with this design in the future once the lower section is developed (outlined in red). After the cows the lower section was used for goose pens, visible as squares in the upper section. These cropping spaces contain too much continuous drop down the slope to allow annual cropping for long due to the risk of erosion, even on this relatively flat land. This shape was originally used for the geese to maximise the area contained for a limited amount of fencing. These were recently surrounded with Tithonia hedges (in green) that will probably be removed as the new design unfolds.

With such limited inputs the space is going to depend on dominant support species the majority of the time. In pre-industrial agriculture it was considered good practice in most places to keep land in fallow (pasture with diverse weeds and periodic grazing) for 9 years, followed by one year of cropping annuals. Continuously cropped land required ten times as much forest to produce duff to fertilise it. To reduce erosion instead of square growing spaces the design will utilise long rows along the long axis of the space that run more or less across the contour of the land. Since I will be growing crops without forming significant raised beds and not engaging in any earthworks I don’t need to pay too close attention to the exact details of the contours of the land, relying instead on biomass and improving soil structure to absorb and retain water. That amount of digging is not feasible by hand on this scale at any rate. This low area is often too wet during rainy seasons so forcing every drop of water into the soil would be counterproductive. As I crop the space I may gradually contour the beds while I am planting and harvesting root crops but this will probably take about a decade.

The support species will need to be chosen carefully. One very useful species is Inga edulis, the ice cream bean. This legume tree fixes nitrogen and draws minerals from deeper in the soil and produces a weed suppressing canopy at a relatively small size. Planted closely in rows 4 m apart the small trees form a canopy that can be cut back before cropping into the bed of mulch produced. The main disadvantages of this tree is its ability to grow very large if unmanaged, so I may need to avoid planting it too close to the power lines, luckily just the lower corner of the space. They can also drop plentiful seed that can form carpets of seedlings, though trees seem to only seed heavily once fully mature. Ice cream bean is easily established from small seedlings and I have about 150 from last summer ready to go once the rains begin. The other major support species will be Tithonia, the shrubby daisy that grows to 2-4 m tall and is covered in golden flowers every autumn that grows rapidly and accumulates phosphorus from the subsoil. It is easily propagated from directly planted unrooted cuttings. It can also self sow, though mice and birds normally eat all the seed before it has a chance, though they come up more reliably in disturbed and cultivated soil. More annoyingly untended plants will lean out and layer into the ground after a few years without pruning, though are fairly easy to remove. A dense planting of Tithonia in my orchard has shown this species is also fairly weed suppressing when mature. They produce huge amounts of tender biomass during warm and wet weather and regrow faster than anything I have ever seen (though this material breaks down rapidly). Even quite thick stems are very easy to cut since it grows so fast, which has the added benefit that the woody waste breaks down fairly quickly when piled up. The final support species will be vetiver grass, a sterile upright clumping grass that forms dense growth that can be cut for coarse mulch. Vetiver is a bit more of a nuisance to propagate, with mature clumps taking a lot of effort to dig up and divide, though they transplant directly during warm and wet weather quite reliably. It is also more work to prune back, and the mulch is fairly coarse but useful on paths.

Combining all these factors leads me to the design below. The outer edge will be planted with a hedge of vetiver grass, leaving room for a second row to be planted outside later if needed, and corner gaps for access gates. This will potentially keep the geese out of the space as needed, though I suspect I will also need to produce other forms of fencing around the most sensitive crops. Vetiver is also excellent at catching eroding soil. Inside the vetiver edge a 1 m path will be left for access with wheel barrows. The yellow lines are Tithonia rows and green Inga rows. I will likely leave a few gaps to allow access across the rows in a few places. This arrangement gives five full inner rows between the support plants for cropping plus two outer half rows. When the support canopy is harvested each row will have either Tithonia or Inga directly adjacent. Tithonia produces twiggy waste suitable for cucurbits to climb over. Inga produces thick leafy mulch more suitable for other crops, plus wood that can either be used as firewood, simple goose fences or added to the Tithonia piles.

Vetiver hedge in brown, Tithonia in yellow and Inga in green. The northern narrow corner is left out due to its low and wet nature, and since it would be difficult to fit sufficient support rows there.

Keeping one species per row makes managing the support species easier. Each species has its own timing of management to avoid issues. Tithonia flowers in May, dropping seed in June, so cutting back after flowering is ideal. Inga flower in spring, fruiting in summer. Either species can be cut at any time as needed. Cutting back in June produces broken down debris piles for cucurbits in the spring and early summer. Cutting back Inga at the same time makes space for growing potatoes in their main crop in winter-spring. Both of these crops can be followed up with maize and amaranth in summer through to autumn, though they germinate better when sowed into cleared ground (possibly cleared with a quick cool burn of remaining debris). The piled up mulch could be saved into autumn for growing a crop of drying tomatoes, carrots, garlic and daikon. All these crops are suitable for this space since they don’t need regular harvesting unlike the vegetables I grow closer to home, and are useful in larger quantities since they can be stored or preserved. Continuing on crops for a year after disturbing the support plants gives a better return on the energy invested in hard pruning the support species and potentially better utilisation of any nutrients imported such as wood ash.

Cross section with vetiver in brown, Tithonia in yellow and Inga in green.

After the more intensive crops they will be followed up with slower crops. Canna produce starchy tubers. Winged yams need tripods but can be interplanted with lima beans. The shady understory could support cocoyam, ginger and turmeric (or they might do better on the half beds on the outer edges). Only one row will be cleared and cropped with intensive annuals at a time, followed by two years of slower crops, followed by two years of letting the support species grow out without cropping. Every year the Tithonia should be cut at least once after flowering, so 240 linear meters of plantings at 1 m apart or 240 shrubs, each taking about two minutes to cut back hard, totalling eight hours of work per year (not including lighter trims around intensive and slower crops). The Inga will need three half rows cut hard per year (one each for the intensive and two slower rows), with tree 1 m apart also taking a bit longer per tree since the wood is more dense, maybe 16 hours per year plus lighter trims. A minimum of three full days of pruning per year seems manageable for this kind of area. Only the intensive crops will require some weeding, while the slower crops will only need this during establishment.

Cross section during cropping, with annuals in orange, followed by two years of perennials in pink and blue (my crude attempt to draw a vine on a tripod). Each year a new row would be cleared for more annuals, working up the hill to allow any run off to go into the perennials.

As for implementation, the old goose pens are currently being hastily prepared for growing some field crops this spring and summer, but the south end of the space is currently just occupied by cobblers pegs. I will begin by cutting down and spraying out the current Tithonia squares, then waiting for the summer rains to begin transplanting first Inga, then vetiver, then Tithonia since it strikes best in mid-autumn. I will mark out corners and row ends with bamboo poles with bright rags to allow me to orient rows as they are extended upwards in the map. I will double check my row spacing by measuring my older pure Inga alley area and mature Tithonia stands. The small area outside the design to the north is the lowest point of the space and tends to get boggy during wet spells. I might try growing asparagus here or some other water loving plant. As gentle contours form along the rows they might move extra water to this place in time. Perhaps I will dig it out into a small pond or paddy.

It is also worth considering failure modes for the space, especially if I cannot input the labour necessary to manage the support species. If the space is untended for about a year the support species will grow over a bit more densely and require a more arduous cut back to get started again. Inga in particular takes many years for individual trees to outcompete their neighbours, and even after 3-5 years the trees respond well to hard cutting back. Layered Tithonia thickets on this time span become a bit messier but the biomass could potentially be burned to kill off layerings in the growing space. If I decide I like one support species more than the other the row spacing is neutral enough to allow me to remove one and replant the other. The goats could also be allowed into the space, though they delight in stripping the bark of Inga once they can’t reach any more leaves. If they were only allowed in for a controlled time they could potentially ringbark the trees but allow the roots to resprout later, resetting the system. Cattle are even harder on these species, smashing Tithonia crowns to pieces, so future owners could fairly easily return to simply grazing beef steers.

As a rough conservative estimate one 80 m double row of potatoes spaced 30 cm apart would yield about 0.5 kg per plant, or 250 kg of spuds, containing about 700 000 kJ, enough energy to keep a person consuming 10 000 kJ a day going for 70 days. Summer maize could yield about as much again, and the perennial rows at the end of their second year would produce approximately as much again, meaning this space can produce a bit over half of a single person’s annual calorie requirement (leaving room for other nutrients as well). Subsistence farming without irrigation, machines and fertiliser only allows one person to feed a bit more than one person. This is the reason why most pre-industrial societies were comprised of 90% peasants and 10% elites of various kinds.

All these are nice ideas for now, leaving me time to turn them over in my mind for a few more months until the rains come and kick me into action. I would love to hear your thoughts and suggestions so I can take them into consideration before I begin.

The space in question to the left of the central fence.

Leave a Reply

Fill in your details below or click an icon to log in: Logo

You are commenting using your account. Log Out /  Change )

Twitter picture

You are commenting using your Twitter account. Log Out /  Change )

Facebook photo

You are commenting using your Facebook account. Log Out /  Change )

Connecting to %s

%d bloggers like this: