Evaluación
de los beneficios y desventajas de los cultivos de cobertura en el uso de
pastos naturales, hacienda San Rafael, Santo Domingo Ecuador.
Evaluation
of the benefits and disadvantages of cover crops in the use of natural gras=
s,
hacienda San Rafael, Santo Domingo Ecuador.
Byron
Fabricio Estupiñán Cox., =
Patricio
Alejandro Merino Córdova.,
Shakespeare Agustín Abarca Córdova. <=
/span>& Daniel Eriel Izquierdo García.
A recent study illustrates the benefits=
of using cover crops against erosive phenomena, to maintain soil fertility=
, allow greater infiltration and storage of water in the soil.
The use of repeated surface works as a =
method to manage the olive grove between rows, for the control of weeds and=
for the conservation of water, leads in the long term to a reduction of th=
e organic substance, to problems of soil compaction underneath. The superfi=
cial layer. And the loss of soil and fertility due to erosion, the risk of =
which increases in mountainous olive groves.
The
sustainable alternative is constituted by the practice of pasture, which, if
properly achieved to minimize competition with the olive, offers several
advantages both in the reduction of soil losses and in water conservation, =
as
well as in the maintenance of fertility, the mineral. And biological. In
addition to the management of a natural lawn, inter-row grass can also be
achieved through the planting of mixed meadows or specific cover crops (cov=
er
crops).
Keywords: Organic
substance, Fertility, Mineral
Resumen.
Un estudio reciente ilustra los beneficios de usar cultivos =
de
cobertura contra fenómenos erosivos, para mantener la fertilidad del suelo,
permitir una mayor infiltración y almacenamiento de agua en el suelo.<=
/o:p>
El uso de trabajos de superficie repetidos como un método pa=
ra
manejar el olivar entre hileras, para el control de las malezas y para la
conservación del agua, conduce a largo plazo a una reducción de la sustancia
orgánica, a problemas de compactación del suelo debajo. La capa superficial=
. Y
la pérdida de suelo y fertilidad debido a la erosión, cuyo riesgo aumenta en
los olivares montañosos.
La alternativa sostenible está constituida por la práctica d=
el
pasto, que, si se logra apropiadamente para minimizar la competencia con el
olivo, ofrece varias ventajas tanto en la reducción de las pérdidas de suel=
o y
en la conservación del agua, como en el mantenimiento de la fertilidad, el
mineral. Y biológico. Además del manejo de un césped natural, el césped ent=
re
hileras también se puede lograr a través de la siembra de prados mixtos o
cultivos de cobertura específicos (cultivos de cobertura).=
Palabras clave: Sustancia orgánica, Fertilidad, Mineral.
Introduction
Not all herbaceous
crops are suitable for use as cover crops, and some are more suitable for
reducing erosive phenomena in olive groves: they have illustrated this in a
recent publication (Ruibérriz de Torres, 2018), some researchers have compa=
red
four botanical species sown in the row of olive trees with a control not wo=
rked
(worked) or with a spontaneous grass. The selected and sown species in the
autumn were a gramineae, Brachypodium distachyon (two-peaked brachipodio), a
crucifer, Sinapis alba (white mustard) and two species of nitrogen-fixing l=
egumes,
Vicia sativa (common vetch) and Vicia ervilia (vecciola) ).
Coverage Crops
Some herbaceous species (mainly belongi=
ng to legumes, grasses and cruciferous families) can be cultivated as inter=
mediate layers (in the period between two main crops in rotation) to conser=
ve or increase the physical, chemical and microbiological fertility of agri=
cultural lands.
Its main function is to bring organic s=
ubstances to the system through the organization of CO2 and nutrients, pres=
ent in the soil at a time of year when the soil would be free of vegetation=
(inter-crop period).
In general, the presence of a vegetatio=
n cover during the intercropping period or during the vegetative stasis of =
the crop, main (arboretum), can offer the following advantages:<=
/span>
1. Increase in content in S.O. from the ea=
rth
2. Improvement of the structure of the lan=
d.
3. Improvement of water infiltration.=
4. Improvement of the traficabilidad.=
5. Control of water and wind erosion (redu=
ction of surface flow, outputs).
6. Control of weed flora.
7. Increase of biological diversity within=
the agroecosystem.
8. Absorption of nitrates and other nutrie=
nts that are otherwise lost through leaching or sliding of the surface=
9. Better nutrient cycle=
10. Possible increase in the availability o=
f nutrients for crops in succession and disadvantages:10.1. The competition with the main culture.<=
o:p>
10.2. Reduction of water availability.
10.3. Possible reduction of nutrient availabi=
lity (immobilization of nitrogen)
10.4. Allopathic effects10.5. Increase in variable costs
The advantages and disadvantages offere=
d by this type of culture depend on the "position" assumed within=
of the rotation, by the species (or species) used and by the "managem=
ent" of the cover crop. Regarding the first aspect (positioning of cro=
p crops in the rotation, crops of the Coverage can be divided into two grou=
ps: permanent or temporary.
The permanents are found mainly in the =
field of tree crops, as in the case of the grazing of the garden; In this c=
ase, the positive effects of the vegetal cover are essentially due to a gre=
ater control, of the phenomena of the water and wind erosion, to a better t=
raffic of the plots, less compaction of the soil, increase of S.O., control=
of the infesting flora in the inter-row, potential absorption of nitrogen,=
free of lye, supply of nitrogen in the case of cover crops of legumes.
The advantages and disadvantages offere=
d by this type of culture depend on the "position" assumed within=
of the rotation, by the species (or species) used and by the "managem=
ent" of the cover crop. Regarding the first aspect (positioning of cro=
p crops in the rotation, crops of the Coverage can be divided into two grou=
ps: permanent or temporary.
The permanents are found mainly in the =
field of tree crops, as in the case of the grazing of the garden; In this c=
ase, the positive effects of the vegetal cover are essentially due to a gre=
ater control, of the phenomena of the water and wind erosion, to a better t=
raffic of the plots, less compaction of the soil, SO increase, control of t=
he infesting flora in the inter-row, potential nitrogen absorption, free of=
bleach, nitrogen supply in the case of legume cover crops. The main perple=
xities related to the grass, the arboretums they derive from the possible f=
orms of competition that the cover crop can exercise against that Principal=
, especially as regards soil moisture. To avoid phenomena of this type, in =
the absence of irrigation, it would be necessary to direct the choice of th=
e species or mixture towards perennial plants characterized by a vegetative=
stasis synchronous with that of greater sensitivity to water stress of the=
main crop (Trifolium subterranean L.) or that it reduces or suspends its v=
egetative development in correspondence with the period of maximum water de=
mand of the garden (Trifolium repens L., Lolium perenne L., Festuca spp., e=
tc.).). Regarding the problem of costs, this goes back to basically for the=
preparation of the seedbed and for the purchase of the seed, since the pos=
sible control of the husk, the grass could imply costs similar to those of =
working the arboretum. The problem of sowing and seed. They could be overco=
me by the use of self-expanding species.
The temporary coverings of plants, on t=
he other hand, occupy the land for a relatively short period of time, among=
other things, greater dynamism within the same change. These in turn can b=
e divided into intercultural and coordinated.
Soil erosion
Erosion is a physical process responsib=
le for continuous remodeling of the earth's surface.Determines the removal of material from=
the surface of the soil. In ecosystems not altered by man, erosion is one.=
Natural phenomenon that accelerate huma=
n activities. To cause a progressive degradation of fertility and therefore=
of the potential productivity of the soil.
Erosion is a complex process influenced=
by numerous factors such as climate, soil type, landscape forms, hydrology=
, vegetation and crops.
Processing and cultivation systems. The=
se factors are related to each other and capable of determining, in differe=
nt measures, the extent of the erosive process and its variations in space =
and time.
Depositions of eroded material can bloc=
k roads. And drainage channels. Sediments can damage natural habitat and de=
grade the quality of surface water. According to some authors in the case o=
f cover crops built to keep the land covered during the year, autumn-winter=
, where technically possible, it is preferable to transcribe them in the pr=
evious crop, in such a way that the "cover crop" can reach proper=
rooting and, therefore, a good degree of coverage already. Immediately aft=
er the collection operations.
Coverage cultivation functions<=
/pre>The soil in nature is always covered, t=
hat is, covered. The bare soil, without grass, leaves other living or decom=
posing material that does not exist naturally. If a land is completely bare=
, it is not alive, as it happens in the desert or in rocky areas. From this=
simple observation we understand that if we want to grow our edible plants=
in the most natural way possible, we must cover the soil. Coverage has man=
y functions:
Protects the earth (and its inhabitants=
) from excessive heat or cold, limits evaporation and, therefore, maintains=
moisture for longer, delays the growth of spontaneous plants by stopping t=
he passage of light necessary for its growth, prevents the compaction of th=
e earth when it rains. These are the main reasons why mulch is used, a comm=
on practice even in intensive production (perhaps made with synthetic mater=
ials), but they are not the most important. The organic matter of the surfa=
ce nourishes the multiplicity of micro and macro organisms that, with their=
work, is transformed into assailable food by the plants. In practice, it a=
llows the fertility cycle to be carried out, without this process, the soil=
would become impoverished until death. But it did not end here. The organic matter is also a powerful s=
ponge that, when it rains, is soaked in water and then released slowly, whi=
ch allows it to reach the underground aquifers. Without this mantle, also m=
ade of humus and roots, the water could not seep into the earth and would s=
lide quickly by dragging behind several elements. Thus the earth becomes im=
poverished and thus the desert is formed. The muddy rivers that rush toward=
s the sea, sometimes destroying the works of man and taking lives, would no=
t exist without the transformations that man has brought to the planet thro=
ughout the millennia, especially with agriculture. You can not imagine retu=
rning to a primordial phase of the Earth, not even wanting it. But much can=
be done if one understands some essential needs of nature: the land wants =
to be covered. Then, when we look at a beautiful field freshly plowed and s=
own in which we can not see a blade of grass, neither alive nor dead, we ar=
e not admiring the beginning of a new cycle of life, but the sure premise o=
f the destruction of the greatest inheritance land. Fertile soil suitable f=
or life.
Cover crops or intermediate crops.
Practices that foresee the next crop or
intermingling with rapid growth and sowing with a high density of legume
species, or less, to reduce soil and nutrient losses (such as nitrogen and
other fertilizer elements). The crop in general has no economic interest and
can be buried before planting the one that has economic interest.
The relationship with parasites.
Keeping the ground covered with a green=
manure crop has several advantages, but it can also cause unexpected probl=
ems. He has faced them, thanks to his experience in the States, Richard Edw=
ards, of the Purdue University of Lafayette, Indiana. "The crop covera=
ge can harbor several insects, some of which can be harmful to the income c=
rops that we will plant later," the teacher explained. In essence, the=
y could create a hospitable environment for some pests that later, after th=
e cover crop, would move on corn or wheat, with foreseeable damages.
On the other hand, it is also possible =
that cover crops provide hospitality to insect’s predators of parasites or =
that they have a deterrent effect towards unwanted species. "Good roof=
management, therefore, can significantly reduce the potential for adversit=
y and favor beneficial species," said the teacher. Among the harmful s=
pecies, the speaker cited Lepidoptera, slugs, insects and other sucking ins=
ects, phytophagous mites, aphids and thrips. "All these parasites can =
cause problems, especially if the main crop follows a period of coverage of=
a few days, which is why I always recommend waiting two weeks between the =
conclusion of the cover crop and the next planting, even if I realize that =
this waiting time can be a problem if you are in a hurry to plant.
In general, underlined Edwards, it is i=
mportant to understand which species are kept in cover crops and what effec=
t they may have on the following. "Naturally, considering what income =
crops will be sown and what species we want to preserve." A typical ca=
se is that of the noctuids, whose females are not attracted to corn, but th=
ey like to lay their eggs in dicotyledonous broadleaf. If we use these plan=
ts as a cover crop and shortly after planting the corn, the noodles, althou=
gh reluctantly, could migrate from the cover crop to corn, and clearly we w=
ill have forced them to this choice ".
Another aspect to keep in mind is that =
crop covers help keep the soil moist. "We must take this fact into acc=
ount when we sow the main crop, because it is more difficult to close the f=
urrow in the humid soil and put the seed in an open furrow exposes it to th=
e attacks of slugs and arthropods." In addition, greater humidity can =
favor fungal diseases, even more insidious than parasitic insects. "Th=
e development of a fungal pathology requires a host plant, a pathogen and p=
articular environmental conditions, therefore, the presence of abundant cro=
p residues can contribute to create the right climate, but it is also true =
that rotation reduces the risk of infections. It is necessary to know well =
the sensitivity of the essences that we use as a cover crop and the plants =
that we will cultivate later and to understand if the former can represent =
a threat to the latter. In addition, it is important to have an interval of=
approximately two weeks between the crops; it is the right time to solve a=
ll these problems. As we say in the United States, you can not sow, weed an=
d go to Florida.
A direct experi=
ence
A "farmer" who certainly does=
not go to Florida after planting is Cameron Mills, owner of 1,400 hectares=
in Indiana. On her land, not irrigated or drained, Mills plants the corn, =
soybeans and wheat in rotation and has left the plow for 15 years, while ni=
ne crops of practice cover. "I did it, he explained during the confere=
nce, to increase the capacity of water retention, break the process created=
over the years, increase the rate of organic matter in the soil, recover n=
utrients and contain weeds. In addition, of course, to stimulate the biolog=
ical activity in the soil. "Objectives that have been reached to a lar=
ge extent. « As for the storage of water, in my land, each processing step =
leads to evaporation of approximately 31 mm / ha the presence of waste, on =
the contrary, contrasts evaporation and keeps the soil cooler in the summer=
. It also improves the structure of the soil, as is known, and increases it=
s porosity.
However, the management of the cover cr=
op (of which Mills has provided an interesting recipe for 15 essences that =
we publish) must be accurate. "Some varieties outperform winter and re=
quire a high level of management. You must choose them according to your eq=
uipment and the supposed completion program. In addition, if we decide to e=
liminate weeds, the treatment should be done with a vital plant and in the =
hottest hours of a sunny day, so that the effect of the product, such as gl=
yphosate, is maximum.
The use of cover crops, during the periods between one crop a=
nd the next, offers a soil cover that can perform many functions: reduce th=
e risks of erosion, nitrogen absorption, limited leaching, and fight agains=
t weeds, improve soil fertility, floor etc.
For the cover crops, theoretically you =
can choose many species, but in practice only a small number (mainly mustar=
d and phallus) is used. In this sense, we are also investigating the potent=
ial of numerous species depending on the services of desired agro systems, =
as well as how to process combinations of species.
<=
pre
style=3D'margin-bottom:12.0pt;text-align:justify;line-height:115%;backgroun=
d:
white'>How to improve the soil with cover crops?<=
/span>
The production of organic matter is an =
important issue for the rural producer. Soil preparation techniques, such a=
s roasting, and planting cover crops that increase soil quality can help or=
even decrease agricultural yield.
American producer Dave Legvold, of Nort=
hfield, in the state of Minnesota, discovered this balance when he took ove=
r the administration of a farm 13 years ago.
The area leased by him was heavily cult=
ivated and poorly drained. "It was horrible," says the producer. =
Legvold, an advocate of band cultivation, wanted to improve the overall qua=
lity of the field. This implemented measures that increased organic matter =
from 1.7% to 5.5% and up to 6.5% in some areas.
According to Chad Watts, executive dire=
ctor of the Conservation Technology Information Center, each floor is diffe=
rent. "We have to treat them case by case," says Watts. In genera=
l, Watts suggests less physical disturbance and more plant diversity. "=
;The more organic matter we have, the better advantages we will have,"=
says Chad Watts, executive director of the Conservation Technology Informa=
tion Center.
Soil receives many benefits from organi=
c matter, says Watts. Proper cultivation and practices that guarantee healt=
hy soil accentuate the benefits. "You can make the cultivation more ef=
ficient with a healthy soil, because it is possible to work the air and wat=
er more efficiently," says Watts. The first measure that producer Legv=
old adopted was to improve drainage. "The previous official worked wit=
h an unusual hydrology with an aiveca plow, going through the grower in the=
fall," says Legvold.
According to Watts, moisture can limit =
the soil. And drainage, if properly adopted, is a good technique for the ag=
ricultural system. "There is a very productive land that needs soil pr=
eparation," he says. With the drainage, the producer Legvold manages t=
o start the crop earlier. "You do not have to wait for the puddles to =
dry out," he says. Reducing soil preparation is the next step in the L=
egvold equation. Soil preparation incorporates organic matter and causes vo=
latilization. This causes the matter to suffer combustion and to become atm=
ospheric carbon.
The preparation injects air into the so=
il. In the fall, when the air leaves the ground, preparation is again neces=
sary. "It's not a healthy cycle, the more preparation you do, the more=
preparation is necessary," says Watts. According to Watts, fifty perc=
ent of the soil should consist of air and water, while the other 50% should=
be organic matter. "If 75% is of soil matter, you have no porosity to=
move air and water, and as you create porosity, you can move them," h=
e says.
Although Watts advo=
cates less soil changes, he believes that direct seeding should not be the =
rule for all farms. "There are management techniques that should be do=
ne on different soils, but there are many places that we do not need to use=
direct seeding," he says. After the transition, the soils may not be =
efficient in the movement of air and water. With fewer changes you can also=
improve drainage, explains Legvold. "If you are patient and allow the=
soil to develop, you will have added stability," says the producer. &=
quot;I can use the planter because the soil is solid while other people can=
not." There is potential to reduce the application of nutrients, but =
that does not happen immediately. "With cover crops, we can change the=
way we think about the nutrition strategy," says Watts. This management favored the nutritiona=
l plan created by Legvold. In addition to inserting nutrients through the r=
oots, you also see the benefits of the soil. "In the past, I had to pu=
t a lot of fertilizer to produce," he says. "The yield increases =
as the soil improves," says Legvold.
Now that the quality of the crop has im=
proved, you can count on the recycling of soil nutrients and use up to 30% =
less fertilizer. Coverage is another practice that helps in the production =
process of organic matter, improving soil quality and fertility. Another ad=
vantage is that Legvold is saving fuel because, with the reduction of soil =
preparation and less need for nutrients, it has made fewer fertilizer appli=
cations during harvest.
Genetic improvement, advances in the ma=
nagement of pests and diseases, better fertilizer management and new techno=
logies boost productivity. So, many times the problems caused by inadequate=
soil management practices may go unnoticed. "There is a phenomenon of=
masking the loss of productivity due to the decrease in soil quality,"=
; says Legvold. "If the quality of the soil continues to decrease due =
to the preparation, we will soon reach a point where we can not overcome th=
e loss of productivity, no matter the strategy."According to Watts, all management prac=
tices have associated implications. Therefore, it is recommended that there=
be a systems approach that promotes adaptations in all areas of the farm, =
with integrated work. "It's a domino effect," says Watts.<=
span
style=3D'font-size:12.0pt;line-height:115%;font-family:"Times New Roman",se=
rif;
color:#212121;mso-ansi-language:EN-US'>
Effective but rejected cover crops=
Coverage crops and water balance of the earth, Observ=
ation “Finca San Rafael Santo Domingo Ecuador”
<=
pre
style=3D'text-align:justify;line-height:115%;background:white'>In the event that the residues of the c=
ultivation culture are dried or devitalized to remain in soil (arboretum or=
non-processing systems), they can, in drought environments, help limit eva=
poration losses and conservation of soil moisture for a longer period of ti=
me during the summer.
Table. One=
Soil humidity at 30 cm depth in relation to different=
plant coverings: % dry weight LM: minimum processing; NL: not processing
|
centeno
|
16,2
en
|
<=
span
lang=3DIT style=3D'font-size:12.0pt;line-height:115%;font-family:"Times N=
ew Roman",serif'>16.0
ab
|
=
18,0
en
|
<=
span
lang=3DIT style=3D'font-size:12.0pt;line-height:115%;font-family:"Times N=
ew Roman",serif'>18.3
ab
|
|
Vicia villosa<=
/o:p>
|
12.7
b
|
14.6
c
|
17.1
ab
|
17,0
bc
|
|
grandiflora Vicia
|
11,4
bc
|
14.4
c
|
15.0
ab
|
16.6
c
|
|
Vicia Vill. + Vicia
grandifl.
|
11,3
bc
|
14.8
c
|
17.1
ab
|
17,5
bc
|
|
Vill centeno + Vici=
a.
|
15,0
por
|
16.5
|
17.2
ab
|
19,5
|
|
suelo desnudo<=
/o:p>
|
11.0
c
|
15,3
bc
|
13,7
b
|
16.8
c
|
With regard to the reduction of evapora=
tion, this is essentially due to the shade of the vegetable coating the res=
ulting soil and another "barrier" effect of the same biomass towa=
rds the water vapor; this effect is, therefore, directly related to the qua=
ntity and remain in the soil of crop residues. The latter, in turn, depends=
on the rate of decomposition of the same waste and therefore on the chemic=
al composition of the biomass (percentage content of lignin and cellulose, =
in particular), and on the administration of the same and the environmental=
conditions in which it operates. In this sense, for example, the residues =
of herbs are much more resistant to decomposition than those of legumes, wh=
ich has a definitely higher C / N, (Rice and Smith, 1884), as mentioned abo=
ve the amount and permanence of crop residues from cover crops. "=
With regard to the reduction of evapora=
tion, this is essentially due to the shade of the vegetable coating the res=
ulting soil and another "barrier" effect of the same biomass towa=
rds the water vapor; this effect is, therefore, directly related to the qua=
ntity and remain in the soil of crop residues. The latter, in turn, depends=
on the rate of decomposition of the same waste and therefore on the chemic=
al composition of the biomass (percentage content of lignin and cellulose, =
in particular), and on the administration of the same and the environmental=
conditions in which it operates. In this sense, for example, the residues =
of herbs are much more resistant to decomposition than those of legumes, wh=
ich has a definitely higher C / N, (Rice and Smith, 1884), As mentioned abo=
ve the amount and the In the Soil is also influenced by the type of technic=
al management of alternation, especially with regard to the choice of the m=
oment of drying of the vegetation cover; In fact, if on the one hand, it ma=
y be advantageous to grow the cover crop as long as possible, in order to o=
btain a greater amount of dry matter (Sullivan, 1991), For another delayed =
devitalization may involve a significant increase in water used by it and t=
herefore a decrease in soil moisture. This can be an advantage if, in rainy=
years, you want the land to dry faster and therefore anticipate the planti=
ng of the next commercial crop, but under normal meteoric conditions, it ca=
n involve serious risks of water stress in the early stages of development =
of the crop that following permanence of crop residues of cover crops "=
;.
Results of Cove=
rage Cultivation observation
All cover crops have shown good develop=
ment potential and good soil cover, even if the latter, but only in the fir=
st quarter of turf establishment, is lower than that of natural turf. Howev=
er, the legume species have demonstrated a capacity to settle and colonize =
the very high inter row in the second year, with an average ground cover be=
tween the vetch and the neighbor of around 90%. Research has shown that run=
off has been significantly reduced (about -77%, on average), compared to wo=
rked soil, cover crops and natural grass: in particular, white mustard has =
been shown to be a particularly interesting because of its ability to devel=
op a very extensive root system, which indirectly increases the permeabilit=
y of the soil and the conservation of the water reserve in the soil. The sp=
ecies could have an additional interest also for the potential biocide, sti=
ll under study, towards pathogens such as Verticillium dahliae.<=
/span>
The reduction of runoff has also affect=
ed the reduction of soil and organic carbon losses: in particular, both bra=
chypodium and mustard have reduced the loss of soil to almost zero due to e=
rosion in simulations of medium intensity rain events (approximately 18 mm =
/ h for 2 or 3 consecutive hours). In all the simulations, the erosive phen=
omena were reduced even more when the events of artificial rain were carrie=
d out after the harvest, due to the mulching effect of the residues that re=
main in the row. In addition to reducing losses of fertile soil, the use of=
selected cover crops offers an even more obvious advantage over the use of=
natural grass, in terms of maintaining inter-row and increasing soil capac=
ity to store water retention. Finally, the use of cover crops also has pote=
ntial from the point of view of the effect of carbon sequestration and the =
increase of organic matter in the soil.
(https://inta.gob.ar/documentos/los-cultivos-de-cobertura-disminuyen-=
la-perdida-de-suelos-por-erosion-hidrica-0)
Conclusions
·
Cover
crops help to prevent erosion, because their plant mass prevents the direct
impact of the raindrop on the ground, slowing the destruction of aggregates=
and
reducing the speed of surface runoff of water. The vegetal cover produced is
anchored to the ground and will not be dragged along with the sediments, as
happens with the waste cut by the harvester. Below the surface, their roots
favor the cohesion and aeration of the soil and after their decomposition t=
hey
leave ducts that facilitate the entry of water into deeper layers.
Bibliographic References.
Rice and Smith. (1884). Coverage Titles. 1-25.
Ruibérriz de Torres. (2018). I scold- 8-35.
Sullivan. (1991). Resources and results analysis of
soil crops. 1-100
Orbegoso, A. and Germán, A. Production of pectinase
enzymes by Actinomycetos in submerged culture using pectin and orange peel.
[Master Thesis in Biotechnology], National University of San Marcos, 2002.<=
o:p>
Bae, S. and Shoda, M. Statistical optimization of =
culture
conditions for bacterial cellulose production using Box-Behnken design.
Biotechnol Bioeng, 2005, vol.90, no.1, p.20-28
Jong Min Lim / et al./. Optimization of medium by
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