Compost Science & Utilization, (2008), Vol. 16, No- 4,220-227

Effects of Mulching Blueberry PlantsWith Cranberry Fruits and Leaves On Yield,

Nutrient Uptake and Weed SuppressionU. Krogmann , B.F. Rogers , and S. Kumudini

2, Department of Environmental Sciences, Rutgers University, Neiv Brunswick, New jersey2. Plant and Soil Sciences, University of Kentucky, Lexington, Kentucky

Integration of local organic wastes as mulches into farm production can provide waste management op-tions and an alternative to landfilling. In 2000, cranberry growers needed ways to dispose of excess cran-berries caused by overproduction and a federal regulation limiting the fruit's marketable production. Thisstudy examined the use of excess cranberry fruits and leaves as mulches on established blueberry plants.The objective of this study was to determine the effects of these novel mulches on established blueberryplant nutrient uptake, fruit yield, selected soil chemical properties and weed suppression. A randomizedblock design was set up and maintained for two years with four different mulch treatments (no mulch, 5.1-cm cranberry fruit, 10.2-cm cranberry fruit and 10.2-cm cranberry leaves). Leaf tissue nutrients (N, P, K,Ca, Mg, Mn, Fe, Cu, Zn, S, B, Al), fruit yield and average fruit size, selected soil properties, weed biomassand number of weed types were determined. In the second year, the fruit yield in the mulched treatmentswas lower than in the control (P<0.05), but not the fruit size. One possible reason is a significant decreasein leaf nitrogen uptake observed in some mulch plots. Weed biomass was significantly reduced along withspecies diversity. This study shows that novel mulches need to be carefully evaluated before being useddue to their potential environmental and plant impacts.

Introduction

Identifying beneficial uses of organic wastes canprovide farmers, food processors and municipalitieswith much-needed organic waste management op-tions. Organic wastes have been used as mulches withpositive effects on plant productivity, soil physicaland chemical properties and weed growth inhibition.Typically, studies have shown mulches decrease tem-perature fluctuation, increase water retention in soil(Bristow 1988, Mbagwu 1991, Monks ct al. 1997, Pick-ering et al. 1998, Pinamonti 1998, Movahedi Naeiniand Cook 2000) and suppress weed growth (Monks ctal. 1997, Ashworth and Harrison 1983). While increas-es in available nitrogen and organic matter are oftenrecorded in mulched soils (Pinamonti 1998, MovahediNaeini and Cook 2000), son:\e studies with organicmulches, typically with high C/N ratios, have shownnitrogen immobilization and little change in soil or-ganic matter after mulch application (Pickering andShepherd 2000, Lloyd et al. 2002). These variations innutrient availability are often dependent on soil typeand type of organic mulch applied. Therefore, it is im-portant to identify the organic mulch characteristics inorder to understand the potential effects the mulchwill have on soil and plants.

An overproduction of cranberries and a dramaticdecrease in cranberry prices in 1999 in the UnitedStates resulted in a federal regulation to limit mar-ketable production of cranberry fruit in 2000 (USDA2000). The nahire of perennial crop production meantthat producers did not have any means of limiting pro-duction of their crop, but were forced to find ways ofdisposing of the crop produced that was in excess oftheir federally regulated limit. Cranberry growersthroughout the United States urgently needed ways tomanage and dispose of excess cranberry fruit harvestin a cost-effective and environmentally sound manner.In New Jersey, cranberry production is in proximity toblueberry acreage. Since blueberry plants require a soilpH in the range of 4.8 to 5.5 (Eck 1988) and the cran-berry fruit is Wghly acidic, investigators proposed theuse of cranberry fruit waste as a mulch in blueberryfields to integrate a locally produced organic wastewith the agricultural market. The close proximity ofthe cranberry fruit waste to the blueberry plants placesthe organic mulch source close to its end use, keepinghauling costs relatively low.

Many studies have found that mulches can be ben-eficial to blueberry plant growth and yield. However,most of these studies only tested the effects of mulchon newly planted blueberry bushes and mainly looked

2 2 0 Compost Science & Utilization Autumn 2008

Effects of Mulching Blueberry Plants with Cranberry Fruits and Leaves On Yield,Nutrient Uptake and Weed Suppressiott

at sawdust and pine bark nuggets as mulch sources(Townsend 1973, Haynes and Swift 1986, Magee andSpiers 1995, Goulart et al. 1997, Spiers 1998). Few stud-ies have examined the effect of mulches on establishedhighbush blueberry plants that grow in sandy acidsoils. Blueberry plants have fibrous, shallow roots thatlack root hairs, making them poor competitors withweeds for nutrients and water (Pritts and Hancock1992). Mulching blueberry plants has the potential torelease nutrients slowly, conserve water in sandy soiland suppress weed growth (Krewer 2001).

By mulching established blueberry plants withexcess cranberry leaves and fruit, growers may ben-efit from the waste product and have an alternativedisposal solution for the over-production of cran-berries. However, the novel mulch needs to beproperly managed and its effect on the blueberryplant and soil needs to be determined. The objectiveof this study was to quantify the effects of fourmulch treatments (no mulch, 5.1 cm and 10.2 cmcranberry fruit, and 10.2 cm cranberry leaves) on a)selected soil chemical properties, b) plant nutrientuptake, c) fruit yield and d) weed suppression.

Materials and Methods

Experimental Design

The research was conducted at the Phillip E.Marucci Center for Cranberry and Blueberry Researchin Chatsworth, New Jersey from December 2000 to No-vember 2002. The field site contained four 1.22-m wideraised rows of highbush blueberry plants, cultivar'Bluecrop'ÍVoccmítmi corymbosumL.) spaced 2.75 mapart that were established in 1982 on approximately0.405 ha of Lakehurst sand (mesic, coated AquodicQuarzipsamments). The highbush blueberry plants,Vacciniutn corymbosum L. cv Bluecrop, were planted1.22 m apart in the row and bordered by the highbushblueberry cultivar, Vaccinium corymbosum cv 11-104.The experiment was set up in a randomized completeblock design with four treatments and six replications.The four treatments were (i) control (no mulch), andthree different mulch treatments, (ii) 5.1-cm and (iii)10.2-cm cranberry fruit and (iv) 10.2-cm cranberryleaves. Each treatment consisted of three experimentalplants with two border plants separating each treat-ment (plot size: 1.22 m x 6.11 m).

Mulch

The cranberry fruit used as mulch for the experi-ment, Vaccinium macrocarpon cv 'Stevens', was har-vested in October 2000 by a local cranberry farmer and

stockpiled before being applied. The cranberry leaveswere waste of the 1999 cranberry harvest at the Rut-gers University experimental station and were storedand aged in a stockpile on-site. Prior to application,both, the cranberry fruit and leaves, were Üioroughlymixed with a front end loader to reduce the variabili-ty of the organic materials.

In December 2000, the mulch was applied at thedesignated depths starting at the hase of the blue-berry plants and ending at the edges of the raisedrow. The mulch depth was re-measured in Decem-ber 2001 and additional mulch was added to adjustthe depth. In 2001, the same mulch was applied as in2000 because the mulch had visibly not changed inthe stockpiles.

Eor the mulch analysis, two to three compositesamples of each of the stockpiled wastes were collect-ed by thoroughly mixing several grab samples in De-cember 2000 and November 2001. To evaluate changesin the land applied mulches, samples were also takenfrom the plots in October 2001 and November 2002.

Standard methods for the examination of waterand wastewater were used for the analysis of thewastes for moisture content, NO -N and electricalconductivity (APHA, 1985). United States Environ-mental Protection Agency standard methods forchemical analysis of water and wastes were used todetermine total Kjeldahl N (TKN), NH -N and pH(USEPA 1979). The waste samples were air-dried,ground, and analyzed for P, K, S, Ca, Mg, Na, Ee, Al,Mn, Cu and 2n using the USEPA SW-846 methods forevaluating solid waste (USEPA,1986). In addition, se-lected waste samples were analyzed for total carhonusing a dry combustion automated system LECO-CNS-2000 (LECO Corp., St. Joseph, Minnesota).

Blueberry Production

Throughout the study, the plants received uni-form recommended split application of 10-10-10 fertil-izer in May and June (Chamberlain & Barclay, Cran-bury, NJ) supplying 67 kg N/ha per year. In 2002,fertilizer was applied at 50% above the recommendedamounts because of the lower than recommended leaftissue N levels (below 1.7% leaf nitrogen) measured in2001 (Pritts and Hancock 1992). Overhead sprinklersapplied irrigation water as needed. Insect control andpruning were conducted according to current prac-tices (Pritts and Hancock 1992).

Plant nutrient uptake was determined by leafanalysis the first week of July in 2001 and the last weekof July in 2002 (Pritts and Hancock 1992). Thirty leavesper treatment replicate were randomly collected fromthe middle shoot. The leaves were gently washed in

Compost Science & Utilization Autumn 2008 221

ti. Krogmann, B. F. Rogers, and S. Kumudini

tap water to rinse off soil or spray residues and airdried until brittle. Total nitrogen was determined us-ing a dry combustion automated system Carlo Erba1500 CNS analyzer (Fisions Instruments, Milan, Italy)and P, K, Ca, Mg, Mn, Fe, Cu, B and Zn were analyzedby CEM microwave digestion (CFM, Matthews, NC)and Thermo Jarrell Ash inductively coupled plasmaspectrometer (Thermo Jarrell Ash Corporation,Franklin, Massachusetts) (Gavlak et al. 2003).

Fruit yield (total weight) was determined by har-vesäng ripened fruit weekly over a four-week periodin 2001 (7/5,7/13,7/24,8/1) and a three-week periodin 2002 (6/24, 7/1, 7/9). Diseased fruit was separatedand weighed. Thirty berries were randomly selectedfrom the non-diseased fruit to obtain a mean freshfruit weight per berry.

Soil Samples

Soil sampling was conducted in the fall and in thespring of 2001 and 2002 to determine if the mulch wasreleasing any nutrients or impacting soil pH. Prior tocoring, n:\ulch or litter was ren:ioved from the sam-pling area to prevent surface organic matter from mix-ing with the soil sample. Three cores (2.5-cm diameterX 15~cm deep) from each treatment replicate werecombined into a single sample and analyzed by theUniversity of Delaware Soil Testing Program. Stan-dard soil tests (pH, electrical conductivity, organicmatter analyzed by a modified Walkley-Black methodand total carbon using a dry combustion automatedsystem LECO-CNS-2000 (LECO Corp., St. Joseph,Minnesota) were conducted along with, NO -N, TKNand Mehlich 1 extractable nutrients (P, K, Ca) Mg, Mn,Zn, Cu, and Fe) analyses (Sims and Wolf 1995).

Weed Production

Weed production and community compositionwere determined each year in August. Weeds weresevered at the soil surface from a randomly placed 30X 30-cm area in each plot. Individual weeds were iden-tified. Weed samples were dried at 70°C for one weekimtil a stable weight w as established and weed bio-mass was determined for each weed (dry weight).

Statistical Analysis

The fruit yield was statistically analyzed using acovariate analysis. This type of statistical analysis wasnecessary due to the initial variability of establishedblueberry plants from bush to bush. The number ofcanes per bush was used as covariant. The covariancehelped discern between the treatments, partitioning

away errors due to plant-to-plant variability in canenumber, normalizing the treatment means (Sokai andRohlf 1981). In 2001, yield data was only availablefrom four replications.

Analysis of variance for changes in soil and plantnutrients and weed biomass and numbers were calcu-lated to compare the different mulch treatments ateach analysis time over the two-year period. Treatmenteffects were tested at the 0.05 level of significance. Gen-erally there were no significant effect of replication.Means were separated using contrast statements andleast significant differences (LSD, P<0.05) were used todetermine stafistical differences between the treatmentmeans (SAS, Cary, North Carolina).

Results and Discussion

Waste Characteristics

The analyses of cranberry fruit and leaves indicat-ed C/N ratios of 125/1 {cranberry leaves) and 168/1(cranberry fruit), acidic pH (2.6 - 3.9) and TKN levelsbetween 0.39% and 0.72% (Table 1). The cranberryfruit mulch had a considerably lower pH and Ca andMn levels than the cranberry leaves, but higher mois-ture, conductivity and K levels. Due to the highermoisture content, cranberry fruit mulch at both appli-cations rates supplied less nutrients than the cranber-ry leaves except for K (Table 1). When compared toother organic wastes, the wastes in this study are atthe higher range for C/N ratio and moisture contentand lowest range for pH (Pickering and Shepherd2000, Rogers eiiï/. 2001).

The cranberry fruit in this study was still intactand contained all its juice, but became mushy overtime. Generally, there are no characteristics reportedin the literature describing the appearance of themulch. However, these characteristics are importantbecause they might affect the farm operation. In thisstudy, the mushy nature of the intact berries whichrolled off the raised beds and were buoyant with rainmade the ground difficult to maneuver and thereforeaffected the blueberry picking. This was not the casefor the cranberry leaf mulch.

As expected, the characteristics of both appliedmulches, cranberry fruit and cranberry leaves(Table 1), changed during the two years of this study(Table 2). The pH of the mulch on the plots increasedover time. Some nutrients (e.g., Ca, Cu) increasedmost likely due to microbial degradation with releaseof mainly CO resulfing in increasing nutrient levelsin the mulch while easy leachable nutrients such as Kdecreased due to leacliing. The effect of the release ofleachable nutrients was also confirmed by decreasing

2 2 2 Compost Science & Utilization Autumn 2008

Effects of Mulching Blueberry Plants with Cranberry Fruits and Leaves On Yield,Nutrient Uptake and Weed Suppression

TABLE 1.Selected characteristics of cranberry fruit and leaves before application and nutrient application rates.

No. of samplespH

C / N

Bulk density

Conductivity

Moisture

TKN

NH4'N

NOj- NOj-N

P

KS

Ca

Mg

Na

Fe

AlMn

Cu

Zn

Dec. 2000

3

2.6

168

0.684

1.98

90

4800

<100

20

1733

7433

600

933

600

100

1577

1814

39

8

16

Nov. 2001

2

3.1-

--1

2.58

87

Dec. 2000

3

3.9

125

0288

0.36

63

5850

150

14

900

6850

5501000

400

<100

-

-

22

3

n

3867

<100

<10

1367

1633

1000

6700

933

167

5073

2620

156

14

39

Nov. 2001

2

3.7_

--

0.74

74

7200

<]00

<10

900

3100

800

5350

800

<100

3035

976

99

6

23

Fruit 5.1 cm

175

<3.6

0.7

63

271

22

34

22

3.6

57

66

1.4

0.3

0.6

1 application rates in Dec.Fruit 10.2 cm

350

<7.3

1.4

126

542

44

68

44

7.3

115

132

2.8

0.6

1.2

Leaves

416<10.8

<1.1

147176IOS721100

1854628217

IS

42

TABLE 2.Selected characteristics of cranberry fruit and leaves after

application collected from experimental plots.

Sample no.

pH

Conductivity

Moisture

TKN

NH^-N

NO,- NO. -N

rK

S

Cü

Mg

Na

Fe

Al

Mn

Cu

Zn

— Oct.5.1-cm

2

4.3

0.39

50

7750

<100

<10

1850

1550

1050

1200

450

150

4165

2480

43

19

30

Fruit2001 "10.2-cm

2

3.8

0.70

51

9150

200

<10

2000

1450

1500

3950

550

200

2775

2500

63

21

48

— Nov,5.1-cm

2

5.4

.2002 -10.2-cm

2

5.0c -'

m z> c**0.12

/d WC53

1 1 1

0.11

t li/t

47

- mg kg' dry wt. -

12450

<100

<10

1050

2000

1200

8000

3850

<100

1685

852

51

12

27

12050

<100

< ! 0

1050

2050

1100

4300

1750

<1001580

1063

43

11

25

LeavesOct. 2001 Nov. 2002

2

5.0

0.06

25

4450

500

<10

1350

300

1050

4450

400

150

5970

2750

95

11

39

24.9

0.19

31

6500

<100

< 10

800

1350

950

8250

1300

< 100

6095

1640

127

11

42

conductivity levels. The ir\crease in TKN might becaused by both, microbial degradation and immobi-lization of N from added fertilizer.

Soil Properties and Leaf Tissue

Some of these changes in the mulch also affectedthe soil properties and the blueberry production. Soilsamples for the plots mulched with cranberry fruitshowed significant, even though small changes insoil pH over the two years (Table 3). Increased soilpHs compared to the no-mulch treatment werefound in Spring 2001 for the 5.1-cm fruit treatment, inSpring 2002 for both fruit treatments and in Fall 2002again only for the 5.1-cm fruit treatment. Other stud-ies found various effects on soil pH depending onmulch or waste characteristics, soil properties andclimatic conditions. Mulches such as oak leaves, pineneedles, pine bark, and spaghnum peat moss containcertain organic acids including tannic acids and resinacids that might increase soil acidity. For example,Duryea et ai (1999) found that at the end of one yearthe initial soil pH of 5 was reduced by pine strawmulch to 4.4, by pine bark mulch and cypress mulchto 4.6, by meialeuca mulch and ground tree pruningsfrom a public utility to 4.7 and by eucalyptus mulch

Compost Science & Utilization Autumn 2008 223

. Krogmann, B. F. Rogers, and S. Kumudini

TABLE 3.Soil Analyses in Spring 2001, Fall 2001, Spring 2002 and Fall 2002 (means within the same sampling time marked by the

same letter are not significantly different (P < 0.05)).

Treatment

Spring 2001No mulch5.1-cm fruit10.2-cm fruit

Leaves

Fall 2001

No mulch

5,1-cm fruit

10.2-cm fruil

Leaves

Spring 2002

No mulch

5,1-cm fruit

10,2-cm fruit

Leaves

Fall 2002

No mulch

5,1-cm fruit

10.2-cm fruit

Leaves

pH

4,2 b

4.4 a

4.2 b

4,4 ab

4.3 a

4.4 a

4.3 a

4,4 a

4,2 c

4.5 b

4,7 a

4,4 b(:

4.4 b

4,6 a

4.5 ab

4.4 b

Conductivitymmhos/cm

0,10 a

0,08 a

0,09 a

0,09 a

0,10 b

0-09 b

0,11 ab

0,15 a

0.13 b

0.12 b

0,15 ah

0,18 a

OM

1,8 a

1,9 a

2,0 a

1,9 a

1,9 a

1,9 a

2,0 a

1.8 a

2.1a

2.3 a

1.9 a

1.8 a

2,2 a

2,1 ab

1,7 b

1,9 ab

N

0.053 ab

0.052 ab

0,071 a

0,050 b

0,051 a

0,059 a

0,066 a

0,054 a

0,062 a

0.065 a

0,053 a

0,054 a

0.068 a

0,062 a

0,061 a

0-067 a

NH;-N

0.76 a

1,01a

1,00a

0,93 a

1,29 a

1,33 a

1.37 a

1,28 a

1,86 a

1,48 ab

1.32 b

1,66 ab

5.58 a

6.75 a

5.97 a

6-12 a

NO^-N

4.1 ab

3,7 b

4-0 ab

4,5 a

3,2 a

3,4 a

3,2 a

3,5 a

2,7 a

2,4 a

2,5 a

2,8 a

1,5 b

1,9 ab

1,6 b

2,3 a

P

31-1 a

17,9 b

26,6 ab

20,0 ab

18 9 a

10.8 a

15.2 a

9,9 a

14,8 a

7,4 a

11^

16,9 a

20.1 ab

12.0 b

16.8 b

27,0 a

K

52.6 a

52,3 a

53,0 a

42,3 b

49,8 a

40.6 ab

41-6 ab

37.6 b

43-1 b

68,0 a

80,4 a

53.6 b

63,5 b

87,1a

87,1a

67-5 ab

ivienL.

Cann'

ich 1 extractable nutMg Mn

rv»

47,7 a

46,1 a

53,3 a

53.7 a

66,8 a

68.6 a

56-5 a

60,3 a

49-4 a

76,3 a

70,5 a

72,9 a

88,6 a

104.9 a

78-3 a

109-4 a

10-5 a

15.3 a

13.1 a

13,9 a

18.6 a

19.4 a

15.8 a

17-4 a

13,3 b

20,2 ab

20.9 a

20,3 ab

23.0 a

23,6 a

21,3 a

27,3 a

0-45 a

0.57 a

0.48 a

0-53 a

1,17a

0,63 a

0,67 a

0,78 a

0,58 a

0,85 a

0,83 a

1,2 a

0,52 b

0-87 b

0.72 b

1,65 a

ricntsZTI

0.77 a

0.78 a

0.85 a

0,93 a

0,94 a

0,89 a

0,82 a

0,83 a

0,97 a

1,15a

1,04 a

0,96 a

1.17 ab

1,57 a

1.12b

1,53 a

Cu

0.25 a

0,23 a

0.27 a

0,62 a

0,23 a

0,24 a

0,22 a

0,23 a

0,20 a

0,19 a

0,19 a

0,19 a

0.23 b

0.24 ab

0.24 ab

0,28 a

Fe

54.5 a

58.2 a

68.5 a

58,7 a

41,7 a

45.9 a

50.6 a

42.3 a

41.0 a

26.1 be

20,4 c

32,9 ab

47.3 a

22,6 c

26.1 be

36,5 ab

to 4.8. Cranberry skins contain quinic, citric and mal-ic acids which might cause increased acidity. On theother hand, wastes high in non-acid cations (e.g., Ca,Mg) such as shade tree leaves (Heckmann andKluchinski 2000) or poultry and pig manures and fil-ter cake (Naramabuye and Haynes 2006) might in-crease the soil pH. Other mechanisms suggested forpH increase are the proton consumption capacity ofhumic materials present in manures and householdwaste composts and the decarhoxylation of organicacid anions during degradation of manures andplant residues (Mokolobate and Haynes 2002;Naramabuye and Haynes 2006). Tn the current studywith surface applied mulches, the mechanisms in-creasing the pH had a greater effect than leaching oforganic acids into the soil underneath which woulddecrease the pH.

In 2001, the soil nutrient analyses did not showmany differences between the no-mulch and themulch treatments. However, more differences werefound in 2002 as the mulch degradation continued.Elevated K levels in the soil (Mehlich I extract) werefound in the cranberry fruit treatments compared tothe control in 2002 (Table 3, P < 0.05) and as a resultelevated levels were also measured in the leaf tissuein these treatments (Table 4, P < 0.05). In Fall 2002,the soil analyses showed elevated Mn levels (Mehlich

[ extract) for the cranberry leaf treatment comparedto the control which was also confirmed by the blue-berry tissue analysis (P < 0.05). On the other hand, in2002, lower Fe levels (Mehlich I extract) compared tothe control were found in the plots mulched withcranberry fruit (P < 0.05). The Fe solubility mighthave decreased due the increased soil pH. The lowerFe soil levels in the cranberry fruit treatments wereconfirmed by the leaf tissue analyses. The Fe levels inthe leaf tissue of all treatments, but especially thecranberry fruit treatment are below the levels (60ppm) recommended by Pritts and Hancock (1992).However, leaf chlorosis, a typical sign of Fe scarcity,was not observed.

As expected, based on the high C/N ratio of thecranberry fruit and leaves, nitrogen in the blueberryleaf analysis (% leaf N) was significantly lower(P=0.05) for some of the mulch treatments (Table 4).Adequate levels of leaf nitrogen in blueberry plantsrange between 1.7 and 2.1% (Pritts and Hancock 1992).Based on these levels, the first year the leaf analysis forall treatments show^ed low nutrient status for nitrogen(1.4% -1.5%) and in the second year, when the fertiliz-er application rates were increased, only the no-mulchtreatment was in the appropriate range. Since the leaftissue samples were collected about three weeks earli-er in the first year and since N levels in the leaf tissue

224 Compost Science & Utilization Autumn 2008

Ejfects of Mulching Blueberry Plants with Cranberry Fruits and Leaves On Yield,Nutrient Uptake and Weed Suppression

TABLE 4Leaf Tissue Analyses in July 2001 and July 2002 (means within the same year marked by the same letter are not

significantly different (P < 0.05)).Treatment

2001

No mulch

5.1-cm fruit

10.2-cm fruit

Leaves

2002

No mulch

5.1-cm fruit

10.2-cm fruif

Leaves

N

1.57 a

1.4] b

1.42 ab

1.45 ab

1.74 a

1.58 b

1.64 ab

1.54 b

P

0.13 a

0.12 a

0,12 a

0.12a

0.12 ab

0.12 ab

0.13 a

0.11b

K

0-4] a

0.42 a

0.42 a

0.44 a

0.49 a

0.53 a

0.61 b

0.51a

Ca

0-25 c

0.36 b

0.45 a

0.31b

0-42 a

0.47 a

0-45 a

0.46 a

Mg

0.14 c

0.18 b

0.21a

0.17b

0.20 b

0.20 b

0.20 b

0.23 a

S

0.13 a

0.12 b

0.12 b

0.13 a

0.13b

0.12b

0.12 b

0.14 a

Fe

42.8 a

41.1a

46.5 a

42.1a

56-8 a

50.8 b

49.9 b

49.4 b

Al

62.6 b

87-9 a

90.1 a

74.8 ab

146 a

126 a

117 a

132 a

Mn

23.4 c

43-8 b

52.8 a

39.0 b

52.4 c

79.9 ab

77.4 b

94.7 a

Cu

ppm

3.7 a

3.9 a

3.6 a

3.4 a

4.9 a

3.9 a

4.0 a

4.3 a

Zn

11.4a

14.2 B

13.1a

11.3 a

11.7 a

11.6 a

11.9 a

11.8 a

B

13.4 b

16.4 b

17-0 b

34.4 a

39.3 b

47.7 b

46.0 b

69.2 a

decrease during the growing season, the scarcity of Nin the first year is even more pronounced. The idealC/N ratio for decomposition is 30/1 with higher ra-tios, as in the mulches in this study, often causing ni-trogen to be sequestered by the microorganisms andlower nitrogen availability to plants. A lower mulchapplication rate (e.g., 5 - 7.5 cm cranberry leaves)might increase the nitrogen levels in the blueberryplant tissue.

Fruit Yield

During the second year, a significantly lowerfruit yield was determined for the mulch treatments(Figure 1). However, the average berry size was notdifferent (Figure 2). This reduction in yield may bedue to several reasons. One reason might be the ob-served nitrogen immobilization by the mulches as in-dicated by the tissue analysis. Another possibility isiron deficiency although this is difficult to prove af-ter the fact. The best way to test if iron deficiency oc-curred would be to determine if the application of fo-liar Fe increased the yield. As discussed, leafchlorosis was not observed.

3.0

2500

Cranbeny Cranberry,1-cm Fruit 10.2-i;m

a 2001

a 2002

Lea\es

FIGURE 1. Fruit yield (means within the same year marked by thesame letter are not significantly different (P < 0.05)).

"a5" 2-0N" 1.53

S. "°5 0.5

0.0

I1

a 2001

ES 2002

No Mulch Cranberry Craníjeny CranberryFnjit 5.1-cm Fruit 10,2-cm Leaws

FIGURE 2. Average fruit size (means witliin the same year markedby the same letter are not significantly different (P < 0.05)).

Since the average fruit size was not different, mostlikely either the flower bud development (e.g., due Ndeficiency) or pollination was affected causing a low-er yield in the second year. The experimental plotswere adjacent to each other, "avoidance" of the flow-ers by the pollinators seems less likely, unless thequality or quantity of the nectar was altered. To betterunderstand the causes of the yield reduction furtherresearch should be conducted.

Weeds

Weed biomass and number of weed species weresignificantly lower in the mulched plots when com-pared to the no mulch treatments (Figure 3 and 4). Thenumber of weed species were significantly lower inthe mulched plots for both years while weed biomasswas significantly different only in the second year(Figure 3 and 4). A broad leaf weed, Goldenrod, solida-go spp., remained the most abundant and persistentweed in each of the plots. Blueberry growers use acombination of pre-emergent herbicides, culturalpractices (discing or mowing) and post-emergent her-

Compost Science & Utilization Autumn 2008 2 2 5

ti. Krogmann, B. f. Rogers, and S. Kumudini

CranberTy Cranberry CrantjerryFruit 5,1-cm Fruit 10,2-cm Leaves

0 2001

H 2002

FIGURE 3. Weed biomass (means within the same year marked bythe same letter are not significantly different (P < 0.05)).

D2001

B2002

INo Mulch CfBnberry Crantjerry Crantjeny

Fruit 5,1-cm Fruit 10.2-cm Leaws

FIGURE 4. Number of weed species.

bicide to control weeds. The selection of the herbicidedepends on the weed present. The most common pre-emergent herbicide is norflurazon (solicam). Since anumber of herbicides are used in blueberry produc-tion, a reduction in weed species could reduce pesti-cide usage by farmers by having farmers target pesti-cide use to the more persistent weed species.

Weed suppression by mulches is caused by thephysical presence of the n:iaterials on the soil surface,and/or by the action of phytotoxic compounds inmulches such as organic acids, ammonia, ethylene ox-ide, and phenolic acids (Ozores-Hampton, 1998,Duryea et al. 1999). However, there have been mixedresults concerning the beneficial effects of alternativeorganic mulches. Municipal solid waste compostsand paper mill sludge compost effectively sup-pressed weeds (Roe et al. 1993; Ozores-Hampton et al.1999) but beneficial effects on soil conditioning andcrop yields varied due to differences in their chemicalcharacteristic and specific requirements of differentcrops (Roe 1998).

Cultivation and crop rotation are typically usedfor weed control in vegetable crop production, grow-ers of established perennial plants such as, blueber-ries, lack the option of crop rotation and cultivation ischallenging due to the narrow rows. Weed reductionpractices for blueberry production include herbi-

cides, shallow hoeing, hand-pulling, and mulching.Some of these practices are labor intensive or too cost-ly. Mulching blueberry plants not only has the poten-tial of suppressing weeds but also of regulating soiltemperature, releasing nutrients slowly, and of con-serving organic matter and soil-water in sandy soil(Krewer 2001).

Summary and Conclusion

This study shows that cranberry fruit and leafmulches have a mixed effect on established blueberryplants. Since blueberry harvest generally involveshand picking, the cranberry fruit mulch can interferewith this process due to the juicy nature of intact fruitmaking the ground more difficult to maneuver. Fur-thermore, a reduced blueberry yield in the secondyear and reduced nitrogen in the leaf tissue wasfound in both years, although the berry size was notaffected. Most likely additional nitrogen fertilizerneeds to be added until the mulch starts to further de-grade and release nutrients. Another cause for the re-duced yield could be iron deficiency although thisneeds to be further evaluated. On the other hand, themulch reduced weed biomass and number of weedspecies. The use of mulch could reduce pesticide us-age by having farmers target the more persistentweed species such as goldenrod.

In conclusion, this research confirmed interactionsbetween soil, plant and applied mulch and showedthat a novel mulch such as cranberry fruit needs to becarefully analysed before being applied. The applica-tion of whole cranberries as mulch for establishedblueberry plants is not recommended due to variousmanagement problems. Instead, the cranberry fruitshould be crushed and composted with other wastes(Ramirez-Perez et al., 2007). However, the increasedpH of the compost might preclude the compost asmulch on established blueberry plants. Due to the easeof management, cranberry leaves are a better option,but should be applied at a lower rate (5-7.5 cm).

Acknowledgements

The authors would like to thank the staff of thePhillip E. Marucci Center for Cranberry and BlueberryResearch for maintaining the plots and the New JerseyDepartment of Environmental Protection, Division ofWatershed Management, and the New Jersey Agricul-tural Experiment Station for financial support.

References

AFHA. 1985. Standard Methods for the Examination of Wa-

2 2 6 Compost Science & Utilization Autumn 2008

Ejfeds of Mulching Blueberry Plants with Cranberry Fruits and Leaves On Yield,Nutrient Uptake and Weed Suppression

ter and Wastewater, 16* ed. American Public HealthAssociation, American Water Works Association andWater Pollution Control Federation, Washington, D.C.

Ashworth, S. and H. Harrison. 1983. Evaluation of mulchesfor use in the home garden. Hort Sei., 18:180-182.

Bristow, K.L. 1998. The role of mulch and its architecture inmodifying soil temperature. Aust.}. Soil Res., 26:269-280.

Duryea, M. L., R.J. English and L.A. Hermansen. 1999. Acomparison of landscape mulches: Chemical, allelopath-ic, and decomposition properties. /. Aboric, 25:88-97.

Eck, P. 1988. Blueberry Science. Rutgers University Press,New Brunswick, New Jersey.

Gavlak, R., D. Homeck, R.O. Miller and J. Kotuby-Amacher.2003. Soil, Plant and Water Reference Methods for theWestern Region. WREP 125. 2"* ed. Oregon State Uni-versity, Corvailis, Oregon.

Goulart, B.L., K. Demchak and W. Yang. 1997. Effect of cul-tural practices on field grown Bluecrop highbush blue-berries, with emphasis on mycorrhizal infection levels.Acta Horticulturae, 446:271-278.

Haynes, R.J. and R.S. Swift. 1986. Effect of soil amendmentsand sawdust mulching on growth, yield and leaf nutri-ent content of highbush blueberry plants. Sei. Hortic-Amsterdam. 29:229-238.

Heckman, J.R. and D. Kluchinski. 2000. Agronomics of landapplication of municipal collected shade tree leaves: 1.Soil properties. /. Sustain. Agr., 17:33-40.

Lloyd, J.E, , D.A. Herms, B.R. Stinner and H.A.J. Hoitink.2002. Organic mulches enhance overall plant growth.Turfgrass Trends. 11 (4):l-7.

Krewer, G. 2001. Suggestions for organic blueberry produc-tion in Georgia. The Southern Region Small Fruit Con-sortium. Fruit Publication 00-1. University of Georgia,Tifton, Georgia.

Magee, J.B. and J.M. Spiers. 1995. Influence of mulching sys-tems on yield and quality of southern highbush blue-berries, p. 133-141. In. Gough, R.E. and Korcak, R.F.(eds), Blueberries: A Century of Research. HaworthPress, Inc., Binghampton, New York.

Mbagwu, J.S.C. 1991. Influence of different mulch materialson soil temperature, soil water content and yield ofthree cassava cultivars. /. Sei. Food & Agr.. 54:569-577.

Mokolobate, M.S. and R.J. Haynes. 2002. Comparative lim-ing effect of four organic residues applied to an acidsoil. Bid. Pert. Soils, 35:79-85.

Monks, CD., D.W. Monks, T. Basden, A. Selders, S. Poland,E. Rayburn. 1997. Soil temperature, soil moisture, weedcontrol, and tomato {Lycopersieon esculentum) responseto mulching. Weed Tecííno/., 11:561-566.

Movahedi Naeini, S.A.R. and H.F. Cook. 2000. Influence ofmunicipal compost on temperature, water, nutrient sta-tus and the yield of maize in a temperate soil. Soil UseManage., 16:215-221.

Naramabuye, F.X. and R.J. Haynes. 2006. Effect of organicamendments on soil pH and Al solubility and use oflaboratory indices to predict their liming effect. Soil Sei.,171:754-763.

Ozores-Hampton, M. 1998. Compost as an alternative weedcontrol method. Hort. Sei., 33:938-940.

Ozores-Hampton, M. , P.J. Stofella, T.A, Bewick, D.J.Cantliffe and T.A. Obreza. 1999. Effect of age of co-com-posted MSW and biosolids on weed seed germination.Comp.Sci. Util., 7:51-57.

Pickering, J.S., A.D. Kendle and P. Hadley. 1998. The suit-ability of composted green waste as an organic mulch:effects on soil moisture retention and surface tempera-ture. Aeta Hortieulturae, 469:319-324.

Pickering, J.S. and A. Shepherd. 2000. Evaluation of organiclandscape mulches: composition and nutrient releasecharacteristics. Arborie. f., 24:175-187.

Pinamonti, F. 1998. Compost mulch effects on soil fertility,nutritional status and performance of grapevine. Nutr.Cyet. Agroecosys., 51:239-248.

Pritts, M. and J. Hancock (eds.). 1992. Highbush BlueberryProduction Guide, NRAES-55. Natural Resource, Agri-cultural and Engineering Service, Ithaca, New York.

Ramirez-Perez, J.C., P.E. Strom and U. Krogmann. 2007.Horse manure and cranberry fruit composting kineticsand measures of stability. Comp. Sei. Util., 15:200-214.

Roe, N.E. 1998. Compost utilization for vegetable and fruitcrops: Municipal waste compost production and uti-lization for horticultural crops. Hort. Sei. 33:1171-1172.

Roe, N.E., P.J. Stofella and H.H. Bryan. 1993. Municipal sol-id waste compost suppresses weeds in vegetable cropalleys. Hort. Sei. 28:934-937.

Rogers, B.F., U. Krogmann and L.S. Boyles. 2001. Nitrogenmineralization rates of soils amended with nontradi-tional organic wastes. Soil Sei., 166:353-363.

Sims, T. and A. Wolf {eds.) 1995. Recommended Soil TestingProcedures for the Northeastern United States. North-east Regional Bulletin #493. Agricultural ExperimentStation, University of Delaware, Newark, Delaware.

Sokal, R.R. and E.J. Rohlf. 1981. Biometry. 2"* ed. W. H. Free-man and Company, New York, New York.

Spiers, J.M. 1998. Establishment and early growth and yieldof 'Gulfcoast' southern highbush blueberry. Hort. Sei,,33:1138-1140.

Townsend, L.R. 1973. Effects of soil amendments on thegrowth and productivity of the highbush blueberry.Giii./. P/fltti Sc/,, 53:571-577.

USDA. 2000. Cranberries Grown in States of Massachusetts,Rhode Island, Conneticaut, New Jersey, Wisconsin,Michigan, Minnesota, Oregon, and Long Island in theState of New York; Establishment of Marketable Quan-tity and Allotment Percentage and Other ModificationsUnder the Cranberry Marketing Order. Final Rule. 7CFR Part 929.

USEPA. 1979. Methods for Chemical Analysis of Water andWastes. Environmental Monitoring and Support Labo-ratory. EPA'600/4-79-020. USEPA, Cincinnati, Ohio.

USEPA. 1986.Tcst Methods for Evaluating Solid Wastes.Volume IB: Laboratory Manual Physical/ChemicalMethods (SW-846). Office of Solid Waste and Emer-gency Response. Washington, DC.

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