Composting Shredded Paper

"G" wrote in, asking if I use shredded paper. Short answer....yes. I personally don't generate a lot of shredded paper myself, but I do have people who donate it to me. And I appreciate getting it. I often dig it into the soil of my flower gardens. I tried once using it as a surface mulch but it had two drawbacks for me. First, the winds tended to blow it around, and second, if wet down, it formed a mat that rain had difficulty penetrating. Thus I prefer to dig it in. 

Above, a compost bin. 

Besides digging it right into the soil, I also use it in the compost bins. It's considered a "brown" ingredient, meaning that it doesn't contribute nitrogen. So it is added along with either fresh green grass clippings or animal manures. It can absorb quite a bit of water, so I make sure to wet it down when it's added to a pile. 

"G" also asked if shredded paper is really 100% clean and safe to use. I can't say that it is. Looking at things realistically, there's hardly anything that is 100% "clean" nowadays. Not the air, the rain, the soil, nothing. Man has contaminated and changed the entire world. And there's not much us little folk can do about it, especially since some of our chemical exposure is mandated by laws and regulations!  While I don't intentionally add lots of toxic chemicals to my gardens, I'm not 100% chemical free. As I've stated in previous blog posts, I take what I deem to be a reasonable and realistic approach. 

Apple Trees in Bloom

Went to check on my apple trees and discovered that they have blooms on them. Oh how that brought back memories of New Jersey! There were lots of orchards in my area there.....apple, peach, pear, nectarine. Those apples were great. 

I find the apples grown in Hawaii are acceptable but nothing to write home about. And unless they're grown high on the slopes of Mauna Loa or Mauna Kea, gardeners here are limited to low chill varieties only. I've only found two types being offered for sale here, and I've got one of each. 

Photo above, these are flowers on my Anna tree. This tree is still quite young, so I only let it produce one apple last year....just so I could say that I got an apple. Yup, a silly ego thing, I'm sure. This year I'll let it keep 3 apples and see what happens. 

Growing apples at lower elevations (I'm at 2400', which is a lot lower than the orchards on Mauna area), is quite difficult due to the Chinese rose beetle. Those beetles can destroy the leaves practically overnight. I haven't yet found a real effective way of controlling them. I truly wish there was a bt product that targeted them. 

First Greenhouse Crops

I've been real eager to get something growing in my new greenhouses. But alas, I haven't finished filling the growing boxes with dirt. But I've started at least.

I've been mining dirt specifically for this project. To the mined dirt I've added 25% compost and mixed it in. That's quite a bit, but the mined dirt doesn't look very fertile. I'm hoping that this ratio of compost to soil will work. Time will tell. 

Above -just planted

I've filled about 6' of the new bed. My planting fingers got itchy, so I planted 6 cucumbers and 10 patio tomato plants. Yeah, I'm pushing it. But boy does it feel good seeing something green in the greenhouse. 

I figure that the cucumbers can be a vertical crop, trellised up the sides of the greenhouse. The tomatoes will be a horizontal crop, spreading out to cover the soil. That's the plan at least. 

Above -ten days later 

My first baby cuke! 

Over the next week or two I'll keep mixing soil and adding plants. 

Potting Soil

Recently a person quizzed me about what I'm using for potting soil to start seeds. Over the past two years I've used a number of different mediums, but currently this past couple of months it's been Pro-Mix BX. Why? Because that's what I can get a hold of locally that actually works well for me. The "working well" is the important part. 

When I first started growing seedlings I tried an assortment of homemade potting mixes...

...garden soil

...sifted compost

...volcanic cinder

...cinder & peat moss

...peat moss

...sand

Each had a drawback that didn't work well for me. I'd say that the cinder & peat moss worked best, but the cinder I had was too coarse. I needed something finer. And the pH was way off, so it only good for starting seeds. 

I could have kept experimenting but I needed to start getting serious about growing food. So I looked to commercial potting soils, something with an established track record. By shear luck I stumbled upon several bales of Pro-Mix that someone wanted to sell. I jumped at it. I was able to get a pallet of Pro-Mix MP, which is an organic version. The basic difference between BX and MP is that BX contains vermiculite and a wetting agent (MP doesn't), plus MP uses about 30% coconut coir in place of spagnum moss. MP cost significantly more than BX, and another drawback for me is that it dries out quickly. I had to water seedlings daily, even on cloudy days. When I ran out of MP I looked around and settled on Pro-Mix BX, the version that my local Ace Hardware sells. 

BX is not considered "organic", I guess because it contains a wetting agent. This doesn't bother me, because as I see it, organic gardeners use Dawn dish detergent as their wetting agent and it surely isn't organic either. I amazes me how gardeners that are so wrapped up in being organic will turn a blind eye to using Dawn, cardboard, newspaper, old carpet, regular garden hoses, plastic rain barrels, etc. All these have traces of chemical contamination and aren't organically "clean". But as I said, it doesn't bother me. Realistically, I can't totally avoid chemical contamination in my life. Not even the air I breathe is chemical free. I just try to be reasonable about things, not fanatical. 

So my current potting soil is Pro-Mix BX. 

Some day when I have the time to fiddle around, I plan to come up with a homemade version. In the end, I'd like to be more self-reliant and have my homestead provide for itself the best it can. I have access to homegrown fresh spagnum moss, though I don't know if that is something to use. I'd have to mix it with something else. I also could gather lots and lots of coconuts locally, which couod be made into coir. But I would have to figure out how to do that. I have volcanic cinder which I would need to clean, sterilize, and sift. I have compost & garden soil which would also need to be sifted and sterilized (fungal diseases abound in the tropics). And I have easy access to lava sand. It's a lot to be figured out. As I said, I don't have the time for that right now. But my gut instinct says that lava sand or volcanic cinder,  along with fine high nutrient compost might be the ticket. 

Using Pine Needles

I have a tree on the place that sheds "needles" like a pine tree. It's called an Australian Ironwood tree. Because of the dense mat of needles, nothing much grows under one of these trees. But it makes harvesting these needles quite easy. 

Why harvest them? Why not? It's a useable resource that my farm provides. And it's renewable, to boot. 

I usually collect a trashcanful whenever I need them. So what are they use for? 

While there can be many uses to choose from, I opt to use them to line the chickens' nest boxes. The birds accept them with no problem. And they don't eat them, as they do grass clippings. They don't kick them out as they do wood chips. They actually appear to like them. It keeps the eggs cleaner as long as I refresh them after each rain. Yes, the girls can muck up a nestbox pretty quickly with mud after a rain. It sticks to their feet and I haven't been able to convince them to wipe their feet off before entering their house. Hey, they tell me that's what the pine needles are for! Ok, ok. I'll just give you fresh ones after each rain. I'll go get more for you. <<<sigh....slave to chickens>>>

Dirty Chickens

"B" contacted me to comment that my chickens were "dirty". Yup, I agree. If you've ever had chickens in a pen, you'll know that they don't use toilet paper and little commodes, they don't wash their feet, they like to dig up the dirt and kick it around. They poo while sleeping, which means that there will be quite a bit of manure beneath their roosting spots in the morning. And if any of them slept in a nestbox, that box will need fresh bedding. It happens because they don't wear diapers, nor are they potty trained. When it rains, they will walk through mud puddles, tromping mud into the nestboxes. Oh my, chickens surely lack manners and social grace. 

My hens spend most of their day is a large roofed pen (10' by 30'). This keeps them safe from dogs, hawks, and mongooses. It means that I can find the eggs in the nest boxes rather than under bushes helter-skelter around the farm. The pen protects them from bad weather. It allows me to harvest manure for the compost bins. The hens run free to scavenge bugs and lizards in the late afternoon for a few hours when it is relatively safe. I'm usually working in the area and can keep an eye out for predators. If they ran loose all day instead of being penned, then their poo would be on the ground someplace around the farm instead of under a perch, in a nestbox, or on the pen litter. Plus the hens would be in danger of being killed by predators. They'd still be poo-ing, but it wouldn't be as noticeable.....except for on the bottom of one's shoes. Yup, I'd be sure to step in it. By the way, I have feral turkeys and pheasants that visit the farm daily, leaving poo piles behind. I have to keep a diligent eye out to avoid piles. 

Yes, chickens can be "dirty". Animals poo and that's a fact of life. It's not something that upsets or worries me. Unlike some commercial farms, my birds are healthy, have no parasites, nor harbor dangerous pathogens that I am aware of. I don't fear working around my flock. I don't mind them being chickens and dirty-ing up the place. Besides, their manure is valuable. 

If one considers poo to be toxic waste, then farming livestock surely isn't for you. 

Multi-Function Chickens -- Permaculture in Action

"D" commented about my permaculture solution to the deep pit beside my driveway. Let me state that I wasn't seeking a permaculture solution per se, but just a sensible solution. And the hugelpit fit the need. Long before I heard the term permaculture or hugelkuktur, I called this project my biotrash pit. In fact, I still call it a biotrash pit. 

My chicken set up is another permie type example of what goes on around here. The chickens eat the farm waste from the gardens. Grass clippings from around the farm goes into the pen for bedding, of which the chickens eat quite a bit of it. The bedding gets harvested regularly and used as fertilizer for the plants. The chickens also get let out to forage almost daily, thus controlling the bug and lizard population. They also eat the occasional mouse they come upon, thus contribute to rodent control. 

Besides fertilizer, the girls give me eggs and meat. Nice bonus. 

And when I let a rooster live in with them each spring, they brood and hatch out new chicks for the flock. 

I didn't create this system solely because it was a permaculture system. No, I did it because it made efficient sense. It's a nice homestead "circle" .....crop waste + bugs + grass fed to chickens produces eggs & meat & baby chicks, which produce fertilizer, which is used to produce veggies & fruits, which produce crop waste, which gets fed to the chickens. 

The homestead hosts other examples of circles and stacked functions. It's just the way it runs on a self reliant homestead. The sheep-donkey-pastures-food forest is another example with the system supporting the livestock and providing human food too. Again, an example including both horizontal and vertical food and resource plants. 

Not only circles and stacking, but interconnected webs. They are all variations on the same ideas. Example : Ponds get runoff from greywater filter systems, ponds support plant life and fish, excess pond water (with fish derived nutrients) goes to garden beds, excess pond plants go to the compost bins, pond water and compost go to produce food, which produce waste to feed livestock (and compost bins), livestock manure used for compost/fertilizer. Compost goes back to the garden beds. Worms from compost bins feed the fish. Aahh, the interconnectedness of all things. 

Undocumented Immigrants

Last Thursday I had a few undocumented immigrants sneak onto my farm. I offered them sanctuary, but probably due fear of being deported if discovered, they moved on. Perhaps looking for a better place to live unnoticed? 

What the heck am I talking about?    ....  Guinea hens! 

Above, hiding in the shadows, I spied three vigilant Guinea hens sneaking up the road. On edge and leery of my truck, I slowly drove by them. In the distance you can see my entrance gate. Pulling through, I left it open as an invitation to the birds. 

Hours went by and I forgot about them until I heard a racket right outside my front door. I caught one of our farm cats, Crookshank (above), heading over to check out the intruders. The cat caused the G hens to spook and break out into a loud racket. If you've ever heard a Guinea hen, you know how loud that can be. And it's quite a distinctive alarm noise. In fact, I'd love to have it as my phone's ringtone. It surely would turn heads in a crowd, don't ya think? 

Ok, now there's four birds. I was quite surprised to see that they came all the way up to the house. I offered them birdseed, but they weren't impressed. I threw about some torn up bread, which they also said "no thank you" to. So I let them be to see what would develop. 

That night they slept in a tree by the chicken pen. In the morning before I left for Maui for three days, I saw a group of FIVE Guinea hens cruising around the front pasture area. I bid them goodbye as I left and wished them luck, but first left numerous piles of birdseed here and there. 

I was hoping they would stay. I hadn't the foggiest idea where they came from, but most likely they had been ditched on the road. It's a common enough occurance here. I didn't know of any neighbor having Guinea hens. But when I returned home on Monday, they were gone. Moved on. Hopefully they found a place that suited them. 

Permaculture -- Stacking Functions

I'm not totally a permaculture farm, but I incorporate a lot of permie principles in what I'm doing. One is called "stacking functions". My driveway biotrash pit is one example. 

This area was a giant deep hole alongside a stretch of the driveway. When the driveway was originally created, soil and rock was excavated and used to build the road, leaving behind a pit that could have easily swallowed my pickup truck. Over the course of time I gradually filled in the hole with chunks of trees, cardboard, weeds, brush trimmings, ....you name. As long as it was biodegradable farm waste, it went into the hole, thus earning the title "biotrash pit"....... rechristened "hugelkuktur pit". Yes, unbeknownst to me at the time, I was building a hugel pit. 

So where does the stacking function idea come into play? The hugel pit is now used for an ideal cite for growing bamboo, which supplies me with building poles. 

And banana trees, which produce bananas for us to eat, young trees for livestock feed, and green waste for compost and mulch.

Under the trees I have sweet potatoes growing, which will provide food for us and the animals. 

Plus turmeric, which is just starting to sprout in the earliest planted spots. Eventually much of the hugel pit will be producing turmeric because it is a shady location. 

Another function, the pit captures and absorbs any rain runoff from the driveway. I don't have much runoff on the farm except from the driveway, so the pit is perfect in collecting and storing this water -- to the benefit of the bamboo, bananas, turmeric, and sweets. 

Finally, some day I see this area being mined for its soil. 

So the stacked factions are: 

...captures rain runoff, prevents flooding

...processes farm waste

...produces its own mulch

...supports food plants (human & animal) without the need to irrigate or fertilize

...produces a building resource (bamboo)

...eventually will be available for soil mining, if needed.

The plants utilize both horizontal and vertical space. Pretty nifty. 

Male Papaya Tree Update

Ok, it's been awhile since the male papaya tree suddenly, out of the blue, produced some fruits. It was quite a surprise. So I've been casually watching to see what developed.  

Two of the smaller fruits aborted while still quite small. And this week I noticed one of the remaining fruits changing color. Yesterday it got to looking rather ripe. Not a large papaya, but I'm just curious if there are seeds inside. 

Got up this morning with the intent of harvesting and tasting this one. But alas, a rat got to it first. 

I found it laying on the ground, well feasted upon. But lo and behold, I could see seeds inside.  

Since these initial fruits were produced, there has been no new ones. Just a profusion of male flowers, but no more female ones. I have no idea what triggered this tree to do this. 

Anyway, the tree is now in the way of where hubby wants to park his car. Since the tree is male, and I have plenty of other papaya trees, this one will go. Tomorrow out comes the chainsaw. 

Mining Dirt

"A", who also lives on Big Island,  wrote to ask me where I get my garden soil from. Quite honestly, I don't buy it. In fact, I'm quite leery about importing soil onto my farm. Bringing in soil could be introducing serious unwanted pests, plant disease, or weeds. I've already got enough little nasties to deal with and I surely don't need more! I've heard of other people who have brought centipedes, stinging caterpillars, little fire ants, and coquis to their places via soil and plants. I accidentally brought a coqui frog  on building lumber, though hubby and I spent several minutes hunting the buggah down that evening. While I will bring in the Kona mulch, which is raging hot and nasties can't survive the heat, I won't bring in non-heated organic matter nor soil. 

So, do I just create all the soil I need? Not hardly! It takes lots of time, effort, and resources to make garden soil. I simply can't do it, at least not enough of it. So where do I get soil? I mine it on my own farm. 

The above area that was mined is about 9' x 16'. It's a spot that is destined to be a parking spot for my truck. I could have simply leveled it out some, topped it with gravel, and parked the truck. But I looked at all that decent soil that would be going to waste. What a waste. So I decided to mine it instead. Out came the pick, o-o bar, and baby sledge. Over the course of several weeks I gradually worked my way. I'd remove rocks, scoop out the soil into waiting buckets, then return the rocks. As I worked, the hole behind me got bigger and bigger as the rocks weren't enough to replace the soil volume I was removing. In spots I dug 2' down, in others 3'. I mined quite a bit of soil, which went down to the gardens. Now I'm in the process of bringing rocks to fill in the rest of the hole. It will take me another couple weeks to finish this project. ....... Yes, I'm most likely crazy. But I did get quite a lot of soil added to my garden areas. 

This sounds like terrible labor, but I don't find it to be so. I only work about a half hour at a time, so it's a nice workout. No need for an exercise gym membership here!!! No need to pay to work out on somebody else's machines. No need to go jogging for half an hour. I can find plenty of good exercise right here on my farm. 

I've moved on from this driveway parking site and am now mining soil down in the dry river bed area. Lots of soil, few rocks, and not nearly the beneficial exercise. I'm currently mining soil for the new greenhouse growing beds. 

Yes, as a real estate agent once noted, my farm has deep soil. But it's all between a lot of rocks! 

Compost Bins

"V" wrote in asking about my compost bins. Actually, he was asking where I bought them. Here on this farm, I tend to make my own when I can, rather than buy it. Here's what I've done......

Above......I decided to build the compost boxes in a heavily shaded spot under a large tree. No crops could be grown there. Plus the spot was adjacent to my driveway, making it easy access to bring organic material to the boxes. So I found 11 sturdy pallets in good condition. 

Above, another view. 

I connected the pallets together using scrap lumber and nails. Since these are permanent boxes, I opted not to tie the pallets together. I wanted them to be more solid than my grow boxes. 

Above, a scrap of plywood nicely secured the outside bottom of the boxes. And where possible, I directly nailed pallets together. 

Above, I drove stakes into the ground and nailed the pallets to them. This firmly is holding the pallets in place. I would prefer to use metal stakes of some sort, but I don't have any at this time. Eventually I'll come across some, and will replace the wooden stakes with metal ones. 

Some of the pallets had closely spaced slats while some had wide gaps. I nailed plywood scraps to the pallets to fill in any gaps. 

With the pallets all secured and wide gaps covered, I started getting the boxes ready for receiving organic debris. I put a 2 inch layer of cardboard in the bottom. I have found that it's easier this way because it helps me determine where the bottom is when I empty out the finished compost. Usually some of the cardboard is still intact and visible. Oooooops. Forgot to line this box with plastic. 

I have a number of recycled black trash bags on hand. I'm using them to line these boxes. Anything that seals the sides could be used....old tarps, poly film, feed bags, etc. The idea is to help retain moisture. In my climate, if I don't line the boxes, they dry out too quickly. 

The black plastic is secured using a nailed on milk jug cap. I've had good success using this method. 

With the box now constructed, it's time to make the fourth wall -- the removable door. I've chosen a lightweight pallet. But it has wide gaps between the slats. 

So I covered them with a double layer of heavy duty cardboard. Just nailed it on using roofing nails. I could have used plywood, but since the door is removable, cardboard can be easily replaced each time I empty the bin. 

On top of the cardboard I applied a black trash bag. In this photo, I haven't nailed it on yet. But I'll use the milk jog caps to secure it in place. 

Almost complete. I need to bring down some bungee cords to hold the door on. I could tie or wire it in place, but I have several of those tight black rubber bungees sitting up in the tool shed. They should work just fine. 

Now it's time to fill it. I'll layer all sorts of organic debris. Layering is one of the tricks I use. Grass clippings. Coarse weeds. Young soft weeds. A little soil, usually what's in the weed roots. Manures. Discarded and foraged stuff that the chickens won't eat. Broken up ohia tree twigs. Mushrooms and fungus if I can find them. Urine. Biochar if I have it. Flyblown slaughter waste and roadkill. Enough water to moisten the layers. I try to have a 50:50 ratio of "greens" to "browns", and balance wet stuff with dry stuff so that the pile doesn't get mucky. 

The main reason I use a hot compost pile is to process items that have seeds, possible noxious insect pests, or pathogens (manure). Otherwise using cold composting (my grow boxes) or simply using organic debris as mulch is just fine too. In my taro patch I use trench composting, and that works just fine. But I don't add manure to trench composting since it doesn't heat up. Composted manure is added afterward. 

I'm a big believer in applying compost to the garden beds. It's great for building soil and adding much needed nutrients for the plants. Most veggies really respond well to the stuff. 

By the way, these particular bins are new. My old ones were 5 years old and falling apart. Time to replace them. I've made six bins so far. I plan to make another 6 alongside these, for 12 altogether. 24 hours after making these, bin #1 is already filled. I try to fill one per week. After the 12 weeks that it takes to fill all the bins, bin #1 will be ready to be emptied. It's composted down to 1/4 to 1/3 the original volume. The contents will have cooled off and be partially decomposed. I'll sift the compost through a 1 1/2" grate, using the sifted material in the garden and returning the coarser stuff to the next compost pile. 

Simple Greenhouses - Update

So here's where I last posted ......... 

Basic greenhouse structure is up. Next step -- build some raised beds. Why? Because the greenhouses are on a pahoehoe shelf (pretty much solid lava rock). There's less than an inch of soil in most spots. I'm making very simple raised beds, 12" deep, out of scrape and recycled plywood. 

Very, very simply constructed. I'm not looking for something that will last years. 

Before adding dirt, I lined the bottom with layers of cardboard to help deter the grass. 

Next, I started filling in with dirt that I harvested from on my own farm. 

Oops. I forgot to cover the plywood with some old black trash bags. I think that keeping the soil off the wood might make it last longer. That's the idea, at least. Luckily I hadn't put much dirt in yet. Then I went back to filling the bed. 

Another quick and simple thing, I temporarily secured the plastic with clothes pins. Once the box is filled and the soil prepared & ready for planting, I'll remove the clothes pins and tack the plastic edges down using a staple gun. 

Once I have the boxes 3/4 filled, I plan to add a goodly amount of compost and some horse & rabbit manure, and till it all before I plant something. Each box needs quite a bit of dirt to fill it, so it's going to take me awhile. 

Last tasks.....besides the soil......is to screen in the ends (to keep out fruit fly and pickleworm moth) and attach some sort of trellis to the greenhouse walls. 

The doorway is really simple for now, just draped screening that I can tie down to an upright 1x4. . Eventually I'll make a more substantial door. 

And in the above photo, and the one two more up, you can see that horizontal bamboo poles have been attached to the inside of the greenhouse. I figure I can tie string or attach some sort of trellis system to them. By the way, the bamboo grows right beside the greenhouses and can be seen rising above the house in the photo above. How conveniently located! Just dumb luck. 

Pallet Fence Pau

It's been almost three years since I first built the temporary pallet fence around the garden. Overall it was a success. It was incredibly cheap, quick, and easy. It did the job. It wasn't as strong as a post & wire mesh fence, but it surely outdid that kind of fence when it came to cost, time, and ease to install. 

Later three years, it's falling apart. The wood that contacted the ground has rotted enough that it is falling apart. Many of the slats are weak and can get broken easily by hand. And since I no longer need the fence (my pasture fences have since been upgraded), it's time for the pallets to go. 

(Above, all gone. Looking down the old pallet fence line, it's once again an open grassy area.) 

Because I never nailed the pallets together in the first place, dismantling the fence is a matter of cutting the ties and pulling that pallet out of the tangled grass growth at ground level. Almost all of the pallets came apart in pieces. 

The slats that lifted off, I stacked. The rest of the tangled pallets need a little more persuasion with a hammer in order to come apart. 

This now all becomes firewood. While I could stack the wood into one of my hugelpits, I'd rather have the firewood. 

Would I ever use this kind of pallet fence again in the future? Sure! 

Ka'u Farm School -- Day 2

The new Ka'u Farm School held its second session this past weekend. As before, there was local interest. I hope it's enough to keep this project continuing. 

Greg gave a walk through of his farm, highlighting some of the organic style practices he's using to produce veggies. Lots of good hints. 

Our local State Rep (and chair of State Ag Dept) attended as a speaker, updating the group on what's happening ag-wise on our island. Topics of interest to the group included the tiny house bill, overnight campgrounds on ag land, the legality of a farm restaurant, water issues. 

"Soils" was the educational subject for the day. Soil science is such a huge topic, even if restricted to just Big Island, that the talk was basically an overview. But it hopefully was enough to get growers thinking about soil pH, soil composition, organic materials, plant nutrients. It's a start. 

So far the school has been more lecture than workshop. But it's not fair to judge this early in the program. It's a project in development. Judging from the talk among the crowd, they are hoping for more practical knowledge and workshop oriented sessions. 

I'm a big supporter of education...spreading the knowledge. So any kind of ag schooling is fine with me. I picked up a few good gems at this second session and I'm looking forward to the next! 

Sweet Potato Container Failure

This was sent to me by "S", who tried growing sweet potatoes in a half barrel container........

"Eight months in a major barrel and this is all I got..... all very deep and right under the plant, by the way.  But lots of unproductive roots thru out.  These cook up bright translucent yellow and are quite sweet.  Waste of time for a container situation, far as I could see.  Could have grown almost three generations of Peruvians for ten times the yield in that same amount of time, and space.  Plants make effective and attractive ground cover, however. "

I don't have any experience using containers for sweets, so I don't know if this would be an expected result.....undersized tubers, long growth period. I'm sure there are climatic factors going on here, but also variety factors too. 

Growers often say how the non-commercial varieties of sweets are fickle. Some years they produce, some years nary a tuber. Some parts of a field will be great, other spots in the same field...nada. That's one of the reasons commercial varieties were developed. There was a need for consistent production. A field that didn't produce after all the time, effort, and expense put into it was a major hurt to a farmer trying to make a living. 

So why grow non-commercial sweets? They often taste way, way better. And there's lots of variations that fit the various nooks people deal with. Some withstand heat and dry, some do good with moist and humid conditions. Some can take a chill, others no. Some taste too sweet for some folks, and others are barely sweet at all. Some produce in rocky or sandy soil, others do fine in compost. Some produce tubers under the mother plant, others spread tubers all around. Some make only a couple giant tubers, others abundant small ones. Some are only good bakers while others are only good fryers. So there's sweets to fit just about every gardeners' situation and desire. But they can be challenging at times. 

I've not even come close to figuring out sweet potatoes. It's always a miracle that I find tubers when I dig them up.