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Introduction
Preserving soil moisture as well as weed control are in
focus of organic production all over the world. The practise
of ground cover is suitable to solve these problems
simultaneously.
According to Libik & Wojtaszek (1973) the practise of
mulching, well known to horticulture, is perhaps as old as
agriculture itself. Mulching with organic materials is highly
beneficial in many orchard crops because it is a traditional
weed control method that offers important potential benefits
by maintaining a high quality soil environment (Hogue &
Neilsen, 1987, Holb, 2002, 2005, 2006).
Moreover, mulching has used generally in organic fruit
farming all over the world due to benefits of it (Skroch &
Shribbs, 1986).
Mulches are not only highly effective in checking
evaporation and in preventing weed growth, but also have
influence on several processes in the soil. The benefits are
variously attributed to the suppression of weed growth, to the
conservation of moisture by reducing evaporation and run off,
to protection from erosion, to increased infiltration of water, to
the increase or decrease of soil temperature fluctuations, to the
enhancement of mineral nutrient availability, to the enhance-
ment of nitrification, to additional nutrients and organic matter
derived from a decomposing mulch, or to the preservation or
improvement of soil structure (Merwin et al., 1994). Moreover,
mulching has a positive effect on nutritional and biological
factors as well (Faust, 1989). On the one hand mulching
produces an increase in the nutrient content of the soil by
leaching of nutrients from the mulch, but at the same time the
entire condition of nutrient availability may be modified for
better or worse by changes induced by the mulch in the
moisture and temperature regimes of the soil. On the other hand
applying mulches increases root length density and brought the
roots closer to the surface (Merwin and Stiles, 1994). In a
review of orchard floor management, Skroch and Shribbs
(1986) provide some general guidelines for several aspects,
including soil quality, water relations, and microclimate. They
statement that the favourable effects on soil quality can be
achieved in the following order: legumes > grass > mulch >
bare ground > cultivation (Skroch and Shribbs, 1986).
Role of floor management in weed control
To grow large fruit, trees must be unstressed and provided
with adequate water and nutrition. Weeds can compete with
fruit trees for both water and nutrients. Research has
demonstrated that weed competition in young fruit trees
reduces tree growth and efficiency, and therefore decreases
fruit production and fruit size (Merwin and Stiles, 1994).
Importance of orchard floor management in organic fruit
growing (nutritional aspects)
Nagy, P. T.1, Kincses, I.1, Lang, T.2, Szôke, S. L.3, Nyéki, J.2& Szabó, Z.2
1Department of Agricultural Chemistry and Soil Science, University of Debrecen, Centre of Agricultural and
Applied Economic Sciences, Faculty of Agricultural and Food Sciences and Environmental Management,
Böszörményi st. 138. Debrecen, H-4032, Hungary nagypt@agr.unideb.hu
2Institute for Research and Development, University of Debrecen, Centre of Agricultural and Applied Economic
Sciences, Debrecen, Hungary
3University of Debrecen, Centre of Agricultural and Applied Economic Sciences, Faculty of Agricultural and Food
Sciences and Environmental Management, Institute of Horticulture, Debrecen, Hungary
Summary: Worldwide research goals and concerns are to soil conservation and improve. This conception is mostly actual in horticulture
where the numbers of high-density plantings are continuously increasing. High-density orchards cause more intensive nutrient and water
uptake. So that the preservation of soil moisture and nutrient level are key factors in qualified fruit growing. On the other hand due to the
climatic changes the water supply of trees will be satisfied among worse conditions than some decades ago. Appearance of water supply
problems and water stress is increased in organic growing, where the number of corrections is limited anyway. Furthermore, floor
management is a successful tool in weed management which causes many problems for organic growers due to the prohibition of synthetic
herbicides. This paper will mainly focus on the nutritional aspects of methods of orchard floor management for growers adopting organic fruit
management to make their production profitable.
Key words: floor management, mulching, weed control, organic growing
International Journal of Horticultural Science 2010, 16 (3): 61–67.
Agroinform Publishing House, Budapest, Printed in Hungary
ISSN 1585-0404
62
Therefore weed control is essential to young tree
establishment and good tree growth and has an important
role in organic production where the methods of it are
strongly limited.
Moreover, it is no doubt that the organic fruit production
is increasing in Hungary in the last few years, but the
production is limited by a lack of effective weed control
methods. When weeds are not managed, reductions in yield
and fruit size occur. Despite of it, currently, organic growers
have few alternatives for weed management and lack
information on which alternatives are most effective.
Growers need much more information on the effectiveness of
weed management strategies in order to maximize yield and
fruit quality.
Furthermore, weed control, particularly in the tree row, is
also more labour intensive in organic orchards. Some
growers report twice as much labour for weed control than in
conventional systems, while other only require slightly more
(Granatstein, 2000b).
Methods of weed control
Current widely used strategies of floor management era
in use, including mechanical tillage, mulching, flaming,
cultivation, living mulch, cover crops and mowing (Table 1).
Each method has disadvantages that determine whether or
not they will be adopted by growers.
Furthermore weed control can be started prior to orchard
establishment and when you have an existing orchard.
Weeds can be controlled mechanically or by manual
cultivation, but control is usually delayed until after
unfavourable weed competition has occurred. Tillage
incorporates crop residues and other organic wastes into
topsoil. However, deep tillage is deleterious to tree roots and
soil moisture relations and should be avoided except in
serious cases of soil compaction. Frequently, very shallow
tillage is recommended to control weeds without damaging
tree roots and without causing undue soil drying. This
shallow tillage permits good water penetration without
exposing additional weed seeds from deeper levels of the
soil, thereby reducing weed pressure over time.
Mowing of sod middles, with shallow tillage along the
tree rows and/or mulches beneath the tree, reduces soil
compaction and erosion and fosters soil microbes and
macrobes. However, sod middles compete for available water
and nutrients. Electrical or flame weeding equipment can
also be used, but may not be practical or safe under orchard
conditions. Careless or uncontrolled fire can kill fruit trees
rapidly (Daar, 1987).
Weed Management Prior to Orchard
Establishment
It is an old statement that easier to manage weeds before
an orchard is established. Cover crops produce a thick stand
that will shade or choke out weeds. Combined with a well-
planned sequence of tillage, cover cropping is an effective
pre-plant weed suppression strategy that also contributes to
soil fertility and stable humus. The basic strategy begins with
plowing under or disking the existing vegetation, ripping to
loosen compaction, planting a cover crop to suppress weed
growth, mowing down and tilling under the cover crop(s),
and finally planting the fruit crop (Kuepper et al., 2004).
Specific cover crops and management strategies must be
varied with location and purpose. The length of the warm
season may allow more than one cover crop to be grown in
succession. Some cover crops may also be cut and allowed to
regrow.
Legume cover crops of purple hull peas (cowpeas),
crotolaria, and sesbania all demonstrated good-to-excellent
weed suppression, while supplying nitrogen and biomass to
the soil.
Weed management an established
organic fruit orchard
Very important to maintenance orchard floor manage-
ment during growing season to can be control erosion,
improve the soil, and provide beneficial insect habitat.
The orchard floor – the tree rows and alleyways – can be
managed in a variety of ways, using tillage or mowing with
cover crops, grazing, or mulching.
A system that provides full ground-cover provides the
best protection against erosion. However, a ground cover that
is actively growing in the summer uses up water. This is a
severe disadvantage in irrigated orchards where water is
limited and expensive.
Where they are adapted, orchard grass, fescue, and other
cool-season grasses are practical fruit crop for water. With
proper fertility management, these grasses can also provide
plentiful mulch. Likewise, grasses are a good choice in apple
orchards, for example, where the excess nitrogen provided
by legumes can actually reduce fruit yields.
Many warm-season legumes are deep-rooted and
compete with the trees for water. Normally, they should not
be allowed to grow under the tree canopy. However,
Nagy, P. T., Kincses, I., Lang, T., Szôke, S. L., Nyéki, J. & Szabó, Z.
Table 1. Commonly used mulching materials
Organic materials Inorganic materials
Straw Breakstone
Straw with manure Plastic foil
Manure Agro-textile
Sawdust Shredded paper
Bark mulch
Turf
Cover crops (grass, legume, hay etc.)
Natural weed cover
Green manure
Source: basic on Hrotkó (2003)
63
leguminous ground covers can provide significant nitrogen
to fruit trees or vines (Haynes, 1980). Grass and legume
ground covers alike promote water infiltration and hold the
soil in place during the rainy season. Ground covers help
maintain and increase soil organic matter, which increases
the soil’s ability to retain moisture. Cool season legumes,
such as bell beans, vetches, and clovers, also can achieve
these goals (Kuepper et al., 2004).
Cover crops
Orchard cover crops can perform four main functions.
They prevent soil erosion and reduce soil compaction from
equipment; improve soil quality and nutrient cycling; and
improve orchard.A good cover crop might be considered one
that has limited competition with the tree, is a poor habitat
for rodents and other pests while being a good habitat for
beneficial species, and can improve soil quality (Granatstein,
2000a).
When you managing a ground cover you should state
your objectives and take into the following considerations
and aims in order of priority:
– suppress weeds,
– break up soil compaction,
– add organic matter to the soil (increase tilth, water
infiltration rates, and water-holding capacity),
– enhance soil fertility (nitrogen fixation),
– attract and sustain beneficial insects,
– serve as a trap crop for pests.
In addition, you must take into account the climate,
rainfall pattern, soil type, and potential for soil erosion
because these parameters basically determine your choosing.
Characteristics of cover crops should be considered
before using. The main questions are the following:
Does this cover crop have a tap root? Will it regrow if
mowed? Does it fix nitrogen? How much biomass does it
produce? Is it fibrous? How long will it take to break down?
Will I need to mow or chop it to speed its decomposition?
When should I incorporate it? Will it reseed itself?What is its
potential to become weedy if it goes to seed? Does it attract
insects? What kinds? Will it serve as beneficial insect
habitat? Is it a host for pests? Can it be used as a trap crop?
(Kuepper et al., 2004).
Animal manures
Animal manures are the most common amendments
applied to the soil. In floor management they are used as
laying down on the soil surface. The quantity of nutrients in
manures varies with type of animal, feed composition,
quality and quantity of bedding material, length of storage
and storage conditions (Dewes and Hunsche, 1998; Loch,
2000).
A typical application of 10 t ha-1 of farmyard manure
from housed organic cattle will contain 30 kg of N, 35 kg of
P2O5and 60 kg of K2O (Loch, 2000). In organic systems it is
particularly important to conserve manure nutrients for both
economic and environmental reasons. Composted manure
thus has a more long-term role in building soil fertility, and
has been shown to be more effective in building soil
microbial biomass and increasing activity than uncomposted
manure. Livestock manures influence soil fertility by two
major routes, through physical effects associated with
organic matters and also through the return of nutrients in
dung and urine.
Mulches
Mulching is a powerful weed management strategy that
can also contribute to good soil management, if appropriate
natural materials are used. After a planting is established,
weeds can be suppressed by applying thick layers of mulch.
Organic mulches are usually applied in a circle around tree
trunks or vines, and down the whole row.
Schupp, 2004 reported that a three- to four- foot-wide
weed-free strip under the trees is maintained to lessen the
competition between trees and weeds. This is particularly
important during the first several seasons of the orchard.
Newly transplanted trees have impaired root systems and this
further weakens the ability of the trees to compete with
weeds. An effective weed management program fosters rapid
early tree growth and early fruit production, resulting in a
faster return on investment.
Mulch materials may include straw, spoiled hay, leaves,
yard trimmings, woodchips, and sawdust. Many of these
materials are inexpensive. Still, it’s wise to weigh the
benefits and risks of each, including hauling costs and the
risks of their containing impurities and prohibited materials
(Kuepper et al., 2004).
Because organic mulches decompose over time, they
require periodic re-applications in order to continue
suppressing weeds. Mulches can provide adequate weed
control if renewed every one or two years, but are expensive,
and create a favourable habitat for voles and rodents.
Further advantage of mulching is that their decom-
position provides other benefits. The decomposition of
mulches contributes organic matter to the soil in the long
term, but ties up mineral nutrients in the short term,
especially N, the lack of which can be limiting to tree growth
and productivity. Coarse shredded bark or woodchip mulch
will decompose more slowly than finer materials and is less
favourable to voles (Merwin, 1995). Bark or woodchip mulch
should be supplemented with hand or flame weeding when
the trees are young (Schupp, 2004).
Mulching with organic matter enhances soil aggregation
and water-holding capacity (Haynes, 1980). Researchers
from 1937 to the present have consistently found that
mulching is the best orchard-floor management system for
retaining moisture (Skroch & Shribbs, 1986).
Kesner (1989) pointed out that mulching was as effective
as irrigation in encouraging tree growth.
Importance of orchard floor management in organic fruit growing (nutritional aspects)
64
Mulching reduces the soil temperature as well, which has
other aspects on growing. Growth in the spring could be
delayed, and transient micronutrient deficiencies do occur
under cold soil temperatures. Cooler soil temperatures are
not particularly favourable for freeze-prone or frost-sensitive
crops, as lower soil temperature means less energy in the soil
to warm trees on cold nights. Too, mulches inhibit the release
(as well as the absorption) of radiant energy, which could be
important on cold nights. Thus, mulches should be applied to
cold- sensitive crops only after the danger of late frost has
passed (Sauls et al., 2005).
Organic mulches can have positive effects on tree growth,
with improvements in soil quality and shifts toward beneficial
nematodes (Granatstein, 2000a).
Organic mulches provide slow-
release nutrients for the long-term
health and fertility of the soil. Research
indicates that potassium, phosphorus,
and nitrogen (primarily from the slow
breakdown of the mulch) are more
available in mulched systems than in
non-mulched systems (Haynes, 1980).
Some growers express concern that
sawdust may acidify their soil or bind
nitrogen in the soil. However, these
effects are minimal if the sawdust is not
tilled into the soil.
Wood chips have been used as
successful mulches. However, since
wood chips have a high carbon:nitrogen
(C:N) ratio, their breakdown in the soil
may immobilize nitrogen reducing its
availability to the trees.We suppose that
this effect may be minimal because the
sizes of wood chips are large enough
that they are not rapidly incorporated
into and decomposed within the soil.
One main problem of mulching is to
ensure sufficient mulching material.
Raising organic matter on the
plantation is one way to ensure
sufficient, clean mulching material.
Farm-raised hay grown outside the
orchard can provide weed-free mulch.
Cover crops may be grown between
tree rows, mowed, and gathered around
the trees. Some small-scale growers use
the biomass from orchard alleyways,
cutting cover crops with a sickle-bar
mower and hand-raking the material
under the trees. Larger-scale operations
often use forage wagons, straw-bale
spreaders, or specialized equipment to
mechanize mulching jobs.
Another problem is the monitoring
system of incoming production.
Gowers must monitor the incoming
product and remove any trash to keep undesirable material
out of their fields. Growers should ask compost producers
about the sources of their materials and any pesticides that
may persist in them. Of particular concern are clopyralid and
picloram, herbicides that are extremely resistant to
breakdown, even after composting. The sale and use of these
materials is restricted in most of areas.
Geotextiles, foils
For suppress weed growth geotextile mulches, paper or
woven plastic fabrics are using generally. While they allow
Nagy, P. T., Kincses, I., Lang, T., Szôke, S. L., Nyéki, J. & Szabó, Z.
Figures 1. and 2.: Mulching in young non bearing pear orchard (Tedej) (left) (P. T. Nagy)
Mulching in peach orchard (Siófok) (right) (T. Lang)
Figures 3. and 4.: Use of black foil in sour cherry plantation (Újfehértó) (left) (P. T. Nagy)
Grass between rows in an apricot plantation (Boldogkôváralja) (right) (P. T. Nagy)
65
some air and water penetration, they may reduce water
infiltration, whereas organic mulches increase infiltration
(Granatstein, 2000). Geotextile mulches do not provide the
advantages of adding matter and nutrients to the soil, and if
synthetic, they must eventually be removed. Geotextiles have
a high intial cost, though this may be partially recouped in
lower weed control costs over the materials expected field-
life – 5 to 10 years for polyester fabric; 2 to 3 years for paper
weed barriers. Still, some growers find them useful for weed
suppression in orchard, tree plantations, and cane fruit
culture.
Weed barriers by sheet mulching: laying down layers of
cardboard or newspaper and covering them with organic
material has also widely spread in the USA. Sheet mulching
increases the efficacy of organic mulch as a barrier against
emerging weeds. Organic growers should avoid cardboard
that is waxed or impregnated with fungicide, as well as
colour print and glossy paper (Kuepper et al., 2004).
In a mulching study (Hogue, 1998) found that several
organic mulches had positive impacts on water infiltration
and retention while a geotextile mulch reduced infiltration.
Cultivation
Cultivation – using mechanical tillage – is the most
widely used weed-management practice in fruit production.
Some fruit growers have practiced “clean cultivation,”
eliminating vegetation throughout the orchard, but this
system has many disadvantages, even if accomplished with
allowed tillage practices instead of organically prohibited
herbicides. In system cultivation may be limited not reaches
the tree row under the dripline. A bare orchard floor is prone
to erosion, gradual depletion of organic matter, increased soil
compaction, and reduced water infiltration. It’s also difficult
to move equipment through the orchard in wet weather.
Flame Weeding
Flame cultivation uses directed heat to kill weeds. It
works not by burning the weeds but by searing them and
causing the plant cells to rupture. Farmers began using
tractor-mounted flamers in orchard and row crops in the
1940s (Daar, 1987, Holb, 2005). Technology and technique
have both been refined considerably in recent years. Several
tools now commercially available, including flame, infrared,
and steam weeders, make heat a viable option for some weed
management applications.
Nutritional aspects of floor management
As sources of available mulches have diversified, a
revival of interest in this method has recently been
documented (Merwin et al., 1995). Several recent field trials
in humid regions have identified beneficial effects of
mulching on apple tree performance (Merwin & Stiles,
1994), soil moisture content (Merwin et al., 1994) and
biological activity in orchard soils (Hartley et al., 1996).
Moreover, there is little information available concerning the
effects of mulching in high density orchards in irrigated
regions where daily irrigation and fertigation might be
expected to reduce potential nutrient and water stresses. Of
particular interest would be the effect of mulching on several
problems associated with fertigation of coarse-textured soils,
including acidification (Neilsen et al., 1999) and the
development of nutrient deficiency (Neilsen et al., 2000).
Also of interest would be the effect of using mulches in
association with organic waste amendments. Biosolids and
other biowaste amendments have improved the growth of
annual horticultural crops in sandy soils, but their effects in
perennial cropping systems have received little attention
(Neilsen et al., 1998).
Nielsen et al., 2003 pointed out that no increases in leaf
nutrient concentration were consistently associated with
improved tree performance. Notable effects included in
creased leaf P concentration associated with biosolids
application, increased leaf K concentration after alfalfa
mulch application and temporary in creases in leaf Zn and Cu
concentration associated with application of biosolids high in
Zn and Cu. Use of both mulches and biosolids amendments
benefits growth of trees in high density plantings de spite
daily drip irrigation and annual fertigation.
Mulch application most consistently affected tree growth,
as indicated in a long term field trial where cumulative yield
after 5 crop years was increased by surface application of
shredded paper, alfalfa and biosolid mulches. Soil nutrient
status and soil biological activity were altered by surface
mulching and at another site trees were buffered against
moisture stress. Initial growth stimulation from mulching
was not sustained at a site where excessive irrigation reduced
N availability. Rotovation of a biosolid-amendment to 0.3 m
depth prior to planting improved the P-nutrition and initial
growth of apple. Amendment treatment did not always affect
apple tree performance (Nielsen et al., 2004).
Mulch increased root length density and brought the roots
closer to the surface. The mulch also increased the
concentration of calcium, potassium, and magnesium in the
soil and the soil’s cation exchange capacity (Lang et al.,
2001).
Marsh et al., 1996 reported in a long term experiment that
after four years, the tree row mowing treatment had
significantly increased soil pH, available P, K, and Ca, and
total N. Soil organic carbon was 4.4% with the tree row
mowing and 2.8% with the in-place control. The choice of
cover crop had less of an influence on soil fertility, and there
were no yield differences. However, fruit quality
characteristics (bitterpit, fruit Ca, background color, fruit
firmness) were influenced by the treatments, in part likely
due to changes in N timing and amount.
The concentrations of soil biomass C, biomass N and
respiration rates were consistently greatest under the straw
mulch and contact herbicide, suggesting that C and N was
Importance of orchard floor management in organic fruit growing (nutritional aspects)
66
incorporated into the soil biomass most efficiently under
these treatments. The soil solution nitrate concentrations also
were lowest under straw mulch and contact herbicide. The
straw mulch increased the concentration of K in the surface
soil (0-15 cm) compared to the other treatments, and was
reflected by consistently higher concentrations in the leaves
of trees. The contact herbicide treatment had lower leaf
concentrations of N in most years. The fruit mineral
concentrations reflected leaf mineral concentrations. The
trees growing in the straw mulch had the greatest shoot
growth and those in the contact herbicide treated soil had the
least. These increases are ascribed to the greater conservation
of moisture within the profile during the shoot extension
period. The differences in harvest yield between treatments
were generally small in individual years, however cumulative
differences occurred over 6 crops. The trees in the straw
mulch had the greatest yields and mean fruit weights. The
ground vegetation management systems did not influence
fruit quality except in the second harvest, when yields were
low and the individual fruits were large (Hipps et al., 2004).
Regarding plant uptake several authors stated that there
were no significant differences in any leaf or fruit nutrients in
long term floor management experiments (Shribbs & Skroch
1986; Lang et al., 2001; Hipps et al., 2004).
Nagy et al., 2009 different livestock manures (cow, horse
and pig) and different mulch-matters (straw, pine bark
mulch, black foil) were applied to the surface to test the
effectiveness of these materials. Applied treatments were
divided into two groups according to origin and effect. Their
results can be summarized as follows:
– Our results pointed out that used ground covering
matters divided into more categories regarding its
effect.
– Available N, P and K content of soil was mostly
increased by applying manures.
– Effectiveness of straw, mulch and mostly black foil
was lower.
– Differences were found between nutrient supplying
treatments and those treatments which did not supply
nutrients.
Acknowledgements
Thanks to OM-00042/2008, OM-00265/2008 and OM-
00270/2008 projects for financial assistance.
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