Organic vs. Conventional Foods: Which is Better?

There is quite a debate currently raging over organic verses conventional foods.  Conventional agriculture has the momentum of the last decades and corporate dollars.  But the organic movement is not to be underestimated with their up and coming grassroots power of past decade.  Unfortunately, there is an awful lot of hype and misinformation out there currently.  One side says there is absolutely nothing wrong with crops grown with chemical pesticides, herbicides, and fertilizers.  While the other side says organic is the only way to go for both environmental and health reason.  Well, to be honest, both of these extremes are wrong and lack a balanced perspective.  Both organic and conventionally grown food have their advantages and disadvantages.  And a more rational look at these different methods will make us a little more well balanced.  So, organic food being the latest and greatest thing, lets take a look at some of its advantages, disadvantages, and misconceptions 

Organic Grown Food
Benefits: 
1. Organic crops lack potentially harmful pesticide and herbicide residues.  While there is not a proven connection between pesticide and herbicide residues and illnesses such as cancer there is some connection.  Research very lacking in this area.  My guess is the connection is rather small.
2. Nutrient levels such as vitamins and minerals are almost always higher in organic grown fruits and vegetables of pretty much every type.  There are 60 years of solid scientific research to back this up, no questions asked.  In some cases organic has way more nutrition and in other cases similar nutrition.  Overall however, organic food is slightly more nutritious. 
3. Taste is often better.  Yes, this is my experience and not scientifically based.
4. Lack of chemicals is better for the environment, again lots of scientific basis for this.
5. Generally lack preservatives that contain heavy metals and dangerous chemicals such as arsenic.  Yes, the waxy coating that many fruits and vegetables have on them typically contain heavy metals and other chemicals that serve as preservatives in shipping and marketing.
6. Can be more productive when grown on a smaller scale.
7. Generally encourages farmers to take care of their land and therefore the ecosystem.
Disadvantages:
1. Generally less food is grown overall on a large scale.
2. More manpower is required to grow crops without pesticides, herbicides, and fertilizers.
3. More expensive.  This is partially because of the greater manpower required for growing and the lower productivity.  Mark-up mostly is a premium simply because it is organic.
4. Natural organic pesticides, herbicides, and fertilizers are not always better for health and the environment.  If they are applied in the wrong way they can be harmful.  Generally though, organic is less harmful though.
5. May rot faster due to lack of preservatives.
Misconceptions:
1. Organic grown requires less fossil fuels.  This is not necessarily true and depends completely on the organic growing process as well as how far the food was shipped.  If you are wanting to eat food that require the least amount of fossil fuels to get to your plate, but food that is grown as close as possible to you.

So in the above, I have tried to be as unbiased as possible and let you know where my own biases are.  Most of the above is not even debated as controversial, but is rather accepted as fact.  In my opinion, it is better to eat organic food for health reasons, to avoid chemicals which potentially can cause diseases but especially for added nutritional value.  In addition, I absolutely despise that dangerous metals and chemicals are applied to foods as preservatives.  I also prefer to eat organic for environmental and economic reason being organic generally is better for the environment and I also like helping out the generally smaller scale organic farmers.  And lastly, if you know how to pick out good quality fruits and veggies, the taste is almost always better.

Is it necessary to eat entirely organic?
Absolutely not.  Chemical fertilizers, pesticides, and herbicides are necessary on a limited basis in the agricultural system.  Without these our ability to produce food would be severely limited.  I currently believe that organic production should increase, conventional production should decrease, and they need to meet somewhere in the middle.  Our bodies and the environment are able to handle responsible amounts of these chemicals so there is no reason to completely ban them from you home or the country.  What these responsible levels of chemicals are, I don't know.

Is the conventional food supply safe?
Of course, the next question is: how safe is the conventional food supply?  Again, this is my opinion, I think the conventional food supply is relatively safe.  While chemicals are dangerous and harmful to the environment, the residues on foods are monitored and are reasonable.  Another reason why eating completely organic is not necessary.  While vitamins and nutrients are higher in organic foods, conventional foods still have good levels of these.

So I guess, eat organic when you can and if you can't don't worry about it.  Far better would be to grow your own food in your own back yard and to make sure you are eating all your servings of fruits and vegetables every day.  A backyard organic garden has huge benefits both to the environment and personal health that far outweigh worrying about organic vs. conventional.  And making sure you eat all your daily servings of fruits and vegetables is far more important than eating only one serving of organic veggies.
Overall, the debate between organic and conventional food is important but it needs to be balanced and prioritized.

Soil, Roots, and Desert Plants

 

In no other ecosystem does soil structure influence where plants grow more strongly than in the desert.  Soils in all ecosystems have strong influences on where plants grow, but the effect is particularly strong in deserts. Being most desert plant adaptations center around accumulating and conserving water, and desert soils have strong influences on where water accumulates, this connection between soil and plants makes sense.  Furthermore, desert soils are relatively diverse when compared to soils in other regions.  The presence or absence of argillic and or caliche horizons show how extremely different one soil can be from another in the desert.  Other regions have too much rain to develop nearly impenetrable argillic and caliche horizons.  Or regions with more rain or freezing temperatures create conditions that are too unstable to develop soils as long and as strong as some desert soils.

There are three common soil-plant communities in the desert.  1. Shallow rooted plant communities growing in soils with caliche and or argillic horizons, 2. Deep rooted plant communities growing on soils without caliche or argillic horizons, and 3. deep rooted plants growing in soils with massive amounts of caliche.  Lastly there are also mountain soils which we will not talk about here due to their non-uniform and unstable nature.  Mountain soils often are not considered soils at all in most situations due to their unstable nature.
The different ages of alluvial fans along bajadas determine how these soils and corresponding plant communities are distributed.  Check out this previous blog entry on alluvial fans and desert soils.  An understanding of how alluvial fans are deposited and form bajadas in the desert is important to understanding soil and plant distributions.

The shallow roots of this Foothills Palo Verde are growing just above the whitish layer of caliche.  Erosion has removed the soil above the caliche in this picture.  After erosion, harder caliche is left in place and shallow roots growing just above the impenetrable soil horizon are exposed.

1. Shallow rooted plant communities growing on soils with argillic and caliche horizons
On the upper bajada, the alluvial fan closest to the mountain, shallow rooted plants compose the community. These are older soils on the bajada and therefore have highly developed argillic and caliche horizons.  These horizons are thick and heavy, resisting water infiltration and root penetration.  Though this may seem like extremely poor conditions, most desert plants are highly adapted and even thrive under these circumstances.  Shallow impenetrable soils horizons allow only shallow rooted plants to root themselves.  Shallow roots avoid impenetrable horizons by accumulating their roots just above.  Water pools in the soil above the caliche allowing an abundance for water thirsty plants.  When only caliche is present, slightly deeper shallow rooted plant occupy the area, such as Saguaros and Foothills Palo Verde.  Areas with an arigillic horizon and caliche have the most shallow rooted plants such as Cholla cacti and Triangle-Leaf Bursage.

How to identify these areas:  Reddish colored soils closer to the mountain, shallow rooted plants such as Saguaro, Triangle-Leaf Bursage, Cholla cacti, Foothills Palo Verde.  These areas generally are sloping gently.  In areas of erosion such as along washes whitish colored soils indicating caliche may be present.

A Creosote Brush community growing on light colored soil without caliche or argillic horizons.

2. Deeper rooted plant communities growing on soils without caliche or argillics
The younger alluvial fans far away from the mountain have very little soil development.  This means no argillic or caliche soil horizons allowing for deeper water and root penetration.  Primarily Creosote Brush occupy these areas with their often six foot deep roots.  Shallow rooted plants generally cannot survive in these areas being water penetrates deeper than their roots reach.

How to identify these areas: Lighter colored soils further away from the mountain that are nearly level.  Plants are generally Creosote Brush and sometimes White Ratany, which is parasitic to Creosote.   White Bursage is also often common in these areas.

Desert pavement.  Usually indicates massive caliche development under the surface.  

3. Deep rooted plants growing on massive amounts of cliche
These are extremely old alluvial fans with very thick caliche horizons.  The massive amount of caliche prevents water from penetrating and the only place for plants to grow are through cracks.  Plants are few and far between and typically only Creosote Brush are present.  The soil surface will typically be nearly level, covered with black pebbles called desert varnish, and be far away from the mountain.  Generally these are most common in the western portions of the Sonoran Desert around the Colorado River.

How to identify these areas: Nearly level areas of desert varnish generally far away from the mountain.  Creosote Brush will be about the only plant and they will be few and far between.  Sometimes patches of Teddy-Bear Cholla will be present.

Transitional areas: exceptions to the above rules
Of course, these are not hard and fast rules, they are generalizations.  For example, transitional areas between community and soils 1 and 2 above will often have a mix of Creosote Brush and Triangle-Leaf Bursage, the first being deep rooted and the second shallow rooted.  This typically indicates a poorly developed caliche that allows for the shallow rooted Bursage to grow.  The poorly developed caliche also allows for deep Creosote roots to penetrate.

Also, for plant community-soil 3 above, areas adjacent to desert pavement without the pavement have had erosional disturbance.  This disturbance allows more water to penetrate the soil as well more roots to penetrate.  Typically there is still caliche so these communities are dominated by shallow rooted plants.

So a little knowledge of how to identify soils and about the rooting patterns of specific plants goes a long way in helping you understand the local Sonoran Desert environment.  When exploring the Sonoran Desert, by looking for these indicators you can begin to piece together what is happening along a bajada.

Northern Arizona Juniper Woodlands

Utah Juniper Woodland and Semi-Desert Grassland near Ash Fork, Arizona.  This is the high  elevation portion of the Great Basin Desert.

I recently spent some time exploring Northern Arizonas Juniper Woodlands and Semi-Desert Grasslands.  Arizona is an interesting state in that it has many different desert types including the semi-tropical Sonoran Desert, the hot Chihuahuan and Mojove Deserts, and the cool Great Basin Desert.  Of these deserts they also have high and low elevation portions.  Northern Arizona for the most part is high elevation Great Basin Desert.  West of Williams, Arizona Semi-Desert Grasslands composed of grasses such as Tobosa, Side-Oats Grama, and Galleta dominate below 3000 or so feet.  The area I spent time in was about 4300 feet and had these grasses with interspersed Utah Juniper trees.  Most people do not find these woodlands nearly as attractive, and many consider them a nuisance, compared to higher elevation conifer forests.  Spending a little time in them, observing and absorbing them for what they are will show these are in-fact beautiful and interesting forests to be appreciated.

The most obvious feature of Juniper Woodlands is of course the Junipers.  As trees go, the Utah Juniper is rather small, only growing to 12 feet or so.  Northern Arizona around Ash Fork west of Flagstaff is characterized by poor dry soils, cold wet winters, and hot dry summers.  When most people think of the desert they do not think of trees, grass and snow but the Great Basin Desert of northern Arizona is exactly that.  Amazingly, last winter I got stuck in 24 inches of snow in this same area.  The Utah Juniper and Desert Grassland thrive under these conditions.  

Utah Junipers and Side-Oat Grama Grass growing among basalt rocks.

Hiking among the Junipers a few birds make themselves obvious as the fly from tree to tree, the Scrub Jay and Ringneck Dove.  Both birds are particularly fond of the Juniper, but especially the Jay.  Utah Junipers produce an abundance of marble sized green to brown colored berries these birds depend on.  These berries often remain on the tree up to two years just waiting for some animal or bird to come by.  Yes, it does actually seem that these berries wait for birds to eat them being they not only provide the bird with food, the bird also helps the tree.  When the bird eats the berry, the seed passes through the bird unharmed.  Seeds passed through birds or other animals actually significantly increase their chances of germination and are transported to new locations.  Not only that, Jays may cache, or hide, berries in the ground for later use, which may be forgotten later and grow into baby Junipers.  If it were not for these birds the large berry and seed would simply fall to the ground beneath the tree.   Then, if the seed did germinate it would have to compete with its mother for soil and moisture, which of course is the wrong way to start off life.  So as a result, these birds are responsible for the planting of these Juniper woodlands.

Tobosa and Grama grasses growing in the finer textured soils.

Apart from Junipers, Ash Fork, Arizona is known as the flagstone capital of the world.  Flagstone is a particular type of sandstone that breaks into smooth flat rocks people use as patio pavers.  Numerous flagstone mines can be found among the sandstone and basalt lava flow hills in the area.  This sandstone creates sandy soils while the basalt breaks down into rocky clay soils.  Exploring the area and doing a little examination of the soils, it can quickly be found that Junipers, especially the larger ones, prefer the rockier soils along with Side-oats Grama Grass.  Alluvial, or water deposited, fine textured soils are generally characterized by grasses such as Tobosa, different Gramas, and Gallete.  Also interesting were the numerous very small Junipers within these finer textured soils.  Historically these fine textured alluvial soils have only had grasses being junipers seem to prefer the drier rockier areas.  Fire exclusion during the past century however has allowed seeds carried to these areas by birds and other animals to grow unhindered.  

A Colorado Pinon Pine growing Under the canopy of a Juniper.  This pine most likely was carried here as a seed and planted here by a Scrub Jay.

While almost all of the trees in the area are Utah Juniper, a few small Single-Leaf and Colorado Pinon Pines can be found.  This is quite odd considering I couldn’t find a significant mature pine for miles and great numbers of Pinons are even further away.  How did these small trees get here?  Pinon nuts are large and heavy so they couldn’t have blown or washed here.  The answer lays again in the Scrub Jay.  All these small Pinon Pines likely were carried as seed by Scrub Jays and hidden under the Junipers so they could have a snack later on.  Unfortunately, the Jay forgot and the seed germinated, growing into a small tree.  This is both good and bad for the tree.  In this area at least it got to grow into a tree but there is not enough rain to support a Pinon Pine for long.  Junipers do much better with 12-14 inches of rain annually than Pinons do.  Pinons need at least a few more inches of rain to do well.  

The grassy openness of these woodlands make walking through them quite easy and enjoyable except for the occasional cholla or prickly pear cactus.  The trees are big enough however to make orientation through the area difficult at times.  While it is open, you can’t see far most of the time, so finding your way can be difficult.  This also makes it quite easy for wildlife to make a quick escape.  Elk are abundant in these areas and utilize the Junipers to hide as well as food.  Elk are most commonly seen in the early morning feeding in open grassy areas.  Coyotes also are abundant and can provide some great night time yipping and howling entertainment.  But after a few hours of day light or less, these animals easily hide themselves from intruding humans among the Junipers.

September in the Sonoran Desert

September is one of the more quiet months in the desert.  With heat dropping, things feel a little more relaxing.  Their aren't a lot of really exciting things going on in the desert, but to the person who looks closely there are all kinds of subtleties happening.

September in the Sonoran Desert means the end of monsoon season.  Usually, the month begins with the waning of monsoons and higher humidity.  Later in the month however, humidity drops and the rains end.  Humidity has dropped from dew points in the 50's to the 30's this past weekend.  Temperatures are also dipping into the 90's for highs which is very good news.  Effects from the scant rainfall continue to linger in the desert.  We will have left over mosquitoes and gnats that hatched during the rain we received earlier in September for the next few weeks or so.  There typically are more than the usual butterflies out starting in September also.  Fall bird migration is also just beginning in the desert.  I have already seen a few hawks migrating through the area.  Cacti are also slightly more plump from the rainfall their roots absorbed and stored in their stem tissue.  Other plants such as Occotillos still have their leafs, which will likely only last a few weeks or so.

Monsoon season is also one of the times of year that dry washes run with short lived flash floods.  Unfortunately, this year the rains were far too scant so only washes with an abundance of bedrock in their channels ran.  Fortunately, their was enough rain in most locations to refill some of the water holes in the mountains, which desert wildlife is extremely grateful for.  These waterholes should get a lot of desert animals through the next several months or so.  September does mark the beginning of the Sonoran Deserts second annual seasonal drought.  The most intense annual drought occurs from late April through early July.  After monsoon season a much less intense and less consistent annual drought occurs from late September through late November.  Temperatures continue to drop during this time, humidity is usually slightly higher (but not nearly as high as monsoon season), and rain does happen on occasion during this second drought.  This all makes desert life much more bearable.

Desert Water Part 2

A Sonoran Desert ephemeral drainage the morning after a flash flood.

This post is second in a series of two about desert hydrology.  Very timely, being he have finally had at least a little rain in the past week.  Here is Part 1 if you missed it.

Flash Flood
A few lucky times a year, storms bringing an inch or more of rain move across the landscape.  Storms like these, depending on how hard and fast the rain comes, will quickly saturate soil surfaces.  In these cases, instead of absorbing into the ground, water runs off into small drainage ways, slowly building volume and force along the way.  Small drainage ways join other small drainages and water flow strengthens.  Continued intense rain feeds volumes of water into larger washes creating a flash flood.  All this can take place in a matter of minutes during intense storms.  The fastest I ever encountered was a flood after only 15 minutes of extremely intense rainfall.  Flash floods are a ground breaking and ground building desert phenomena.  Desert landforms are both built and destroyed by flash floods.  Bajadas, the smooth slopes flanking mountain sides, are nearly entirely built by flash floods carrying sediments from the mountain.  Then once established, bajadas will also be destroyed by the powerful erosive action of flash floods.

Flash floods however are few and far between, and as quickly and violently as they appear they disappear.  However, they do not leave however without lasting effect.  For months, and in some cases almost a year, water from the flash flood is held in wash sediments.  Deep roots penetrate deep into wash sediments harvesting this stable reservoir of water.  This is why often, the only location you will find thick vegetation and trees in the desert is along washes.  Often, because of the erosive nature of flash floods plant roots are exposed in washes due to the soils once concealing the roots being washed away.  Many of these trees have obvious rooting patters that make little effort penetrating into the uplands outside of the wash.  Instead, nearly all trees plunge thick roots directly into wash sediments where moisture is stored.  Palo Verde, Ironwood, Mesquite, and Acacia trees of washes all show this rooting pattern.  If you were to dig a hole in one of these washes, a foot or so under the surface you would find a thick network of fine roots in place, ready for water whenever it come down the wash.  But even wash sediments become dry after rainless periods.  If drought persists, some trees will shed leafs to preserve water.  Under continued drought even branches will die to reduce water use.  But these trees stand ready with roots in position.

Animal Life
Animal life responds also to these rain events but in much less dramatic ways.  Some animals, such as Kangaroo Rats, never require drinking water, instead obtaining water from the food they eat.  Other animals such as Mule Deer require permanent drinking water sources.  During drought these animals are constrained to live only short distances from waterholes.   With rainfall however, water holes become more abundant and deer can range far from these more permanent holes.  The greater effect of rain on animals is seen later on as it aides the hydration of young, growing animal populations in good rainfall years.  The boom and bust of animal and bird populations goes right along with the boom and bust of annual rainfall.

A small waterhole in a Sonoran Desert mountain canyon.

During the winter, cooler temperatures allow for the desert to stay wet for months on end some years.  Typically one average winter rainfall of half an inch every month is sufficient for this.  Winter rainfall typically ends the begining of April and the desert quickly heats up and dries out until monsoon season starting in July.  May and June are the driest times of the year and typically no rain falls what-so-ever during these months.  During this time the soil and plants dry out.  Waterholes also dry out leaving only the largest most reliable waterholes wet.  Summer rainfall is a lot different from winter rain.  Summer heat quickly dries out the moisture left after a July or August thunderstorm.  Occasionally moisture can evaporate within hours of a rainfall event.  More often it takes days for the land to desiccate.  In good summer rainfall years though rain every few days can keep the landscape wet for weeks on end.  But as is inevitable, the desert always returns to dry.  Dryness is what defines a desert and dryness is what orchestrates the composition of plants and animals here.  And as the desert dries, desert life clings to water, often thriving in its absence.  But desert life always waits for that next rainfall, longing for the life it gives. 

Desert Water Part 1

Sonoran Desert after a rainfall.  Within days the leafless plants in this photo will sprout leafs.

Well, we had a decent rain finally this past weekend in the Sonoran Desert.  So in honor of that, this post is the first of a two part series on desert hydrology.  Part 2 will be posted this coming Friday.

All desert life clings to water.  As odd as it might sound all desert life is intensely shaped by water.  When passing clouds condense and rain across the landscape a desert raindrop scarcely finds any impediments between it and the ground.  That is, of course if the raindrop doesn't evaporate before hitting the ground, a common desert frustration.  Sparse vegetation allows most rain direct access to the ground, its most logical destination.  However, being most precipitation events are quite small, once a raindrop falls soil moisture is typically short lived, and rapidly evaporates back into the atmosphere, renewing the scarcity of moisture.  This scarcity is exactly what created the desert in the first place and creates the often dusty atmosphere or the semi-frequent dust storm.  Combining together, rain and dust can turn into another uniquely desert phenomena, muddy rain.  All rain, muddy or not, is coveted by desert life.  And all desert rain brings with it cleansing and life.  The once dusty atmosphere is washed crystal clear after rain subsides and plant and animal life is renewed.

Trace Rain
Even trace amounts of rain have an effect on the desert.  If a few raindrops are fortunate enough to fall on black soil crust moisture is readily received by the ground.  Cryptobiotic soil crusts thinly coat desert soils in undisturbed areas.  Most of the year these crusts lay shriveled and dry on the soil surface, with no obvious signs of life.  But even minute trace amounts of rain spring to life microscopic cyanobacteria and fungi composing these crusts.  Once awaken, brittle crusts transform into slightly swollen, softer, and biologically active versions of what they were before.  Cyanobacteria rapidly absorbs sunlight in order to photosynthesize and harvest nitrogen from the air.  Nitrogen is then deposited into the soil, serving nutrients to associated fungi as well as nearby plants.  These crusts cling to water, holding it in the top centimeter of soil much longer then if these crusts were absent.  But hours to days after rainfall, once the soil crusts dry out, they return to their original dry brittle form.

These spine lined ribs of the Saguaro expand apart as the cactus stores water in the stem and shrink together as water is used up.

More Rain
If a fortunate larger rainfall event occurs, say one-half inch, raindrops will penetrate much deeper into the soil bringing to life dormant plants.  As this moisture soaks is it pools above impenetrable caliche soil horizons. Rarely does rain ever penetrate below the caliche line which is typically around two feet below the surface. Shallow rooted plants such as cacti and Triangle-Leaf Bursage are the first to take advantage of this new moisture pooling above the caliche.  Desiccated plant roots rapidly respond by growing new rootlets, exploiting as much of the shallowly penetrating moisture as possible.  New rootlets transport water to the stems of plants which in the case of cacti begin to swell.  After long months of drought, the accordion shaped exterior of a Saguaro cacti appears compressed due to water loss.  Water loss during rainless periods decreases the diameter significantly, leaving a thin anemic looking cactus.  However, as water is rapidly absorbed the accordion shaped exterior expands as the cactus swells and becomes plump.  The cacti chug as much water as fast as they can, storing it in their stem tissue for later use.  This drinking strategy categorizes cacti with other succulents as water storers.  Storage of water within expandable stems serves to supply cacti with water for continuous slow growth and metabolic function months after soil moisture has been depleted and other plants appear shriveled and dry.  Once soil moisture is depleted smaller cacti roots die and are shed while large roots remain intact but enter a state of dormancy.

Ocotillo sprouting new leafs and flowering after spring rains.

Other shallow rooted plants such as Triangle-Leaf Bursage or Brittlebrush also absorb water but at a slower pace.  These plants, known as intensive exploiters, utilize very shallow roots to exploit only shallow soil moisture.  Rather than storing water, these plants instead quickly resurrect seemingly dead crunchy leaves, turning them green again.  Available water is also incorporated into new stems and leafs, growing the plant as fast as possible.  When moisture is depleted new roots are shed, growth stops, and leaves slowly shrivel and are shed.  Plants can become so shriveled and leafless after long rainless periods that they can appear all-together dead.  Some plants such as the Ocotillo only sprout leafs after rainfall, then shedding them as the soil drys.  Other plants prefer deeper moisture and for this reason avoid soils with caliche.  Caliche often prevents rainwater from penetrating deep into the soil, therefore preventing deep rooted plants from establishing themselves.  Younger soils without caliche therefore become the primary home for the deep rooted Creosote Bush and Mesquites.

Friday I will post the rest of this article about water in the desert.  See you then!

Mushroom Hunting

The Perennial Plate Episode 69: Mountain Morels from Daniel Klein on Vimeo.

While I'm not much of a mushroom hunter, I sure would like to be.  Being the desert is about the worst possible place for mushroom hunting I'm sort of out of luck.  Arizona's higher elevations do offer some decent mushroom hunting.  Outside of the desert though, mushroom hunting is an excellent way to get outside and learn about all kinds of things in the outdoors.  Anyone can do it just make sure you have the right field guides for identifying mushrooms and go along with someone that is experienced.  You can learn all sorts of ecological secrets in the process of mushroom foraging.  Of course, never eat something that you aren't absolutely sure of what it is.  For most of North America Morel season is months behind us but for more northern and mountainous regions they can be found in abundance as seen in this video.  This is episode 69 of the Perennial Plate and is filled with interesting ecological facts about Morels as well as great mountain views.  The Perennial Plate also has a great website with weekly videos and blog entries.

Check it out here: http://www.theperennialplate.com/

Sonoran Desert Soil Distributions

Dry mountain canyon wash looking out on the desert below.  Canyons such as this one are the gateways for nearly all soils in the Basin and Range.

When most people think of desert soils they think of rolling sand dunes.  The problem is that sand dunes are not soil at all, rather they are blowing, shifting piles of sediment.  And sand dunes are relatively rare in the Sonoran Desert anyway.  Instead of blowing sediments, the life of Sonoran Desert soils begins as rock in the scattered small mountain ranges common to the region.  A process called weathering breaks down this rock into smaller and smaller particles.  These particles then wash out of the mountain due to heavy rainfall causing erosion, debris flows, or flash floods.  Odd as it might sound, nearly all desert soils are built by these types of water movements through the landscape.  Contrary to intuition, the very rock and dirt fabric of the desert is carved out and formed by water.

Knowing the above process is essential to understanding soil distributions in the Sonoran Desert.  And knowing where soils are located is key to understanding the Sonoran Desert landscape.  Both hydrology and plant communities are strongly defined by the desert soil.  In a previous post on soil mapping we discussed generally how to locate soils in the landscape.  In this post we will discuss specifically how to locate soils in the Sonoran Desert.  Believe it or not, desert soils are complex in structure but relatively easy to map.  The general rules that we discussed before apply in a rather neat fashion.

The alluvial fan is circled in white in the below image.  The canyon through which all the sediments came from for the alluvial fan is lined with blue.

Sediments washed off a mountain are deposited in landforms called alluvial fans.  Deriving their name "alluvial" due to being water deposits, and "fan" from the fact that they are often fan shaped.  These fans are created through flash floods or debris flows which cascade sediments through mountain canyon washes to basins below.  Typically, once these flow reach the wash outlet, sediments are deposited radiating out from the outlet in a fan like shape.  Over long periods of time these fans can become quite large, often merging with other fans being deposited from other canyon washes nearby.  Then, from this first alluvial fan, sediments can be eroded off and deposited below forming a second alluvial fan.  This process of erosion and deposition can repeat itself several times and several alluvial fans can be deposited in succession away from the mountain range.  Each of these successive fans will produce a unique soil.  Erosion and deposition will often destroy the fan-like shape initially present when first deposited.

This diagram shows generally how alluvial fans, or soils, are arranged in a bajada.  Each soil  developed from an alluvial fan.  Each fan was deposited in succession outward from the mountain.  The oldest fan, or soil, being where it is labeled soil 1.  The youngest fan, or soil, is labeled soil 4.  Soil 1 and 2 are the oldest and in the Sonoran Desert are generally very similar with red soil, an argillic, and caliche horizons.  Soils 3 and 4 are also similar to each other and generally lack argillic and caliche horizons, also lacking red coloration.

The resulting succession of different alluvial fans radiating out from a mountain side is known as a bajada.  Each section of the bajada is a different alluvial fan with a different soil type.  These individual fans, or sections of the bajada, can be identified by basic soil mapping principals.  Each fan soil will have a particular soil color, horizons, a general rock type cover, slope, plant community, and landscape position.  Soils, or fans, closer to the mountain, higher up the bajada are much older.  Soils, or fans, further away from the mountain and lower on the bajada are much younger, in-fact they may have just recently been deposited.  The older a soil is the redder it will be (previous post on soil color), therefore upper bajada soils are red in coloration while younger lower bajada soils lack red coloration.  The red coloration indicates the presence of caliche and argillic soil horizons in most cases (previous post on desert soil horizons).  Upper bajadas will also have steeper slopes while lower bajadas will nearly be flat.  Upper bajadas will also generally have rockier soils and fewer rocks will be present lower in the bajada.

An upper bajada soil surface.  Cacti of several species, Palo Verde, Triangle-Leaf Bursage,  and some Creosote make up this upper bajada plant community.  These plants, except the Creosote, have generally shallow roots which are adapted to caliche and argillic soils common to upper bajadas such as this one.

Soils in the desert seem to have a particularly strong effect on plant life.  We will discuss this further in a future post but desert plants are a strong indicator of what lays below the surface.  Some plants prefer argillic and caliche horizons while others can stand them.  Generally shallow rooted plants such as Chollas, Prickly Pears, Saguaros, Triangle-leaf Bursage, and Foothills Palo Verde prefer caliche and argillic horizons in some circumstances.  Therefore shallow rooted plants prefer upper bajadas.  Creosote bush having deeper roots prefer the absence of caliche and argillics, therefore preferring lower bajadas.

A lower bajada soil surface.  This plant community is primarily Creosote.  There are a very few cacti also present though.  The deep roots of creosote prefer the absence of impeding caliche and argillic horizons upslope on the bajada.

End of year Garden Economics Update

One of my gardens waiting for fall planting which will happen in the coming month.

Well, its been a hard summer for gardening.  July was hot, and usually we get at least some break from the heat during monsoon season, but not this year.  Monsoon season was a huge disappointment with less than one inch of rain.  The lack of rain resulted in an August where every single day was over 100 degrees and 12 of those days over 110 degrees.  Everything suffered as a result.  I really didn't put much effort into the garden  due to the heat.  But here are the results:

College garden
Tomatoes 16lbs. 15oz., $50.64 ($2.99/lbs.)
Green onions 1lbs. 15oz. $4.65 (0.59/lbs.)
Summer squash 4lbs. 2oz., $12.33 ($2.99/lbs.)
Eggplant 1lbs. 8oz., $2.99 ($1.99/lbs.)
Total hours: 5
Total calories burned: 1530
Calories produced: 2042
Net calories:  512
$ spent: $0.00
$ produced: $70.61
Net $: $70.61

Home Garden
Zucchini 3lbs. 8oz., $10.47 ($2.99/lbs.)

Chives 4oz., $2.99 ($1.99/2oz.)
Basil 12oz., $17.94 ($1.89/2oz bunch)
Tomatoes 7lbs. 3oz., $21.49 ($2.99/lbs.)
Cucumbers 3lbs. 1oz., $9.16 ($2.50/lbs.)
Eggplant 3lbs. 12oz., $7.46 ($1.99/lbs.)
Total hours: 5
Total calories burned: 1530
Calories produced: 1534
Net calories: 4
$ spent: $0.00
$ produced: $72.50
Net $:  $72.50

Totals since October 2010
College garden:  
$ Totals: $193.63+$70.61=$264.24
Total hours worked: 29.75
Calorie totals:8350+512=8862

Home
$ Totals: $221.12+$72.50=$293.62
Hours worked: 30.25
Calorie totals:5054+4=5058


As for rain in the near future... there seems to be no sign of it.  We really haven't had any good rainfall for a year and a half.  Also, I will be getting the garden ready for fall planting in the coming weeks so what you see here will be the year end totals.  Being this is the first year I tracked my produce I learned a lot.  I know of many ways I can increase my yield pretty easily for next year.  For one, I will be limiting my up front costs for planting as well as trying to plant a little earlier.  Both of these things will help a lot.  Between the two gardens I grew a total of $557.86 on about 150 square feet.  Not sure how this compares with other peoples gardens.  My gardens were bigger then 150 square feet but I learned that I only used that much space effectively.  I'll know better for next year.  Overall produce works out to be about $9.30 per hour of work, which is not too bad.  


I am already planning my fall garden and will be watching temperatures closely for planting.  I will give an update on my fall planting plans within the next month.