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Compost Science & Utilization, (2008), Vol. 16, No- 4,220-227 Effects of Mulching With Cranberry and Leaves On Yield, Nutrient Uptake and Weed Suppression

U. Krogmann , B.F. Rogers , and S. Kumudini 2, Department of Environmental Sciences, Rutgers University, Neiv Brunswick, 2. 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- caused by overproduction and a federal regulation limiting the 's marketable production. This study 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 blueberry plant nutrient uptake, fruit yield, selected soil chemical properties and weed suppression. A randomized block 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 biomass and number of weed types were determined. In the second year, the fruit yield in the mulched treatments was lower than in the control (P<0.05), but not the fruit size. One possible reason is a significant decrease in leaf nitrogen uptake observed in some mulch plots. Weed biomass was significantly reduced along with species diversity. This study shows that novel mulches need to be carefully evaluated before being used due to their potential environmental and plant impacts.

Introduction An overproduction of cranberries and a dramatic decrease in cranberry prices in 1999 in the United Identifying beneficial uses of organic wastes can States resulted in a federal regulation to limit mar- provide farmers, food processors and municipalities ketable production of cranberry fruit in 2000 (USDA with much-needed organic waste management op- 2000). The nahire of perennial crop production meant tions. Organic wastes have been used as mulches with that producers did not have any means of limiting pro- positive effects on plant productivity, soil physical duction of their crop, but were forced to find ways of and chemical properties and weed growth inhibition. disposing of the crop produced that was in excess of Typically, studies have shown mulches decrease tem- their federally regulated limit. Cranberry growers perature fluctuation, increase water retention in soil throughout the urgently needed ways to (Bristow 1988, Mbagwu 1991, Monks ct al. 1997, Pick- manage and dispose of excess cranberry fruit harvest ering et al. 1998, Pinamonti 1998, Movahedi Naeini in a cost-effective and environmentally sound manner. and Cook 2000) and suppress weed growth (Monks ct In New Jersey, cranberry production is in proximity to al. 1997, Ashworth and Harrison 1983). While increas- blueberry acreage. Since blueberry plants require a soil es in available nitrogen and organic matter are often pH in the range of 4.8 to 5.5 (Eck 1988) and the cran- recorded in mulched soils (Pinamonti 1998, Movahedi fruit is Wghly acidic, investigators proposed the Naeini and Cook 2000), son:\e studies with organic use of cranberry fruit waste as a mulch in blueberry mulches, typically with high C/N ratios, have shown fields to integrate a locally produced organic waste nitrogen immobilization and little change in soil or- with the agricultural market. The close proximity of ganic matter after mulch application (Pickering and the cranberry fruit waste to the blueberry plants places Shepherd 2000, Lloyd et al. 2002). These variations in the organic mulch source close to its end use, keeping nutrient availability are often dependent on soil type hauling costs relatively low. and type of organic mulch applied. Therefore, it is im- Many studies have found that mulches can be ben- portant to identify the organic mulch characteristics in eficial to blueberry plant growth and yield. However, order to understand the potential effects the mulch most of these studies only tested the effects of mulch will have on soil and plants. on newly planted blueberry bushes and mainly looked

220 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 stockpiled before being applied. The cranberry leaves (Townsend 1973, Haynes and Swift 1986, Magee and were waste of the 1999 cranberry harvest at the Rut- Spiers 1995, Goulart et al. 1997, Spiers 1998). Few stud- gers University experimental station and were stored ies have examined the effect of mulches on established and aged in a stockpile on-site. Prior to application, highbush blueberry plants that grow in sandy acid both, the cranberry fruit and leaves, were Üioroughly soils. Blueberry plants have fibrous, shallow roots that mixed with a front end loader to reduce the variabili- lack root hairs, making them poor competitors with ty of the organic materials. weeds for nutrients and water (Pritts and Hancock In December 2000, the mulch was applied at the 1992). Mulching blueberry plants has the potential to designated depths starting at the hase of the blue- release nutrients slowly, conserve water in sandy soil berry plants and ending at the edges of the raised and suppress weed growth (Krewer 2001). row. The mulch depth was re-measured in Decem- By mulching established blueberry plants with ber 2001 and additional mulch was added to adjust excess cranberry leaves and fruit, growers may ben- the depth. In 2001, the same mulch was applied as in efit from the waste product and have an alternative 2000 because the mulch had visibly not changed in disposal solution for the over-production of cran- the stockpiles. berries. However, the novel mulch needs to be Eor the mulch analysis, two to three composite properly managed and its effect on the blueberry samples of each of the stockpiled wastes were collect- plant and soil needs to be determined. The objective ed by thoroughly mixing several grab samples in De- of this study was to quantify the effects of four cember 2000 and November 2001. To evaluate changes mulch treatments (no mulch, 5.1 cm and 10.2 cm in the land applied mulches, samples were also taken cranberry fruit, and 10.2 cm cranberry leaves) on a) from the plots in October 2001 and November 2002. selected soil chemical properties, b) plant nutrient Standard methods for the examination of water uptake, c) fruit yield and d) weed suppression. and wastewater were used for the analysis of the wastes for moisture content, NO -N and electrical Materials and Methods conductivity (APHA, 1985). United States Environ- mental Protection Agency standard methods for Experimental Design chemical analysis of water and wastes were used to determine total Kjeldahl N (TKN), NH -N and pH The research was conducted at the Phillip E. (USEPA 1979). The waste samples were air-dried, Marucci Center for Cranberry and Blueberry Research ground, and analyzed for P, K, S, Ca, Mg, Na, Ee, Al, in Chatsworth, New Jersey from December 2000 to No- Mn, Cu and 2n using the USEPA SW-846 methods for vember 2002. The field site contained four 1.22-m wide evaluating solid waste (USEPA,1986). In addition, se- raised rows of highbush blueberry plants, cultivar lected waste samples were analyzed for total carhon 'Bluecrop'ÍVoccmítmi corymbosumL.) spaced 2.75 m using a dry combustion automated system LECO- apart that were established in 1982 on approximately CNS-2000 (LECO Corp., St. Joseph, Minnesota). 0.405 ha of Lakehurst sand (mesic, coated Aquodic Quarzipsamments). The highbush blueberry plants, Blueberry Production Vacciniutn corymbosum L. cv Bluecrop, were planted 1.22 m apart in the row and bordered by the highbush Throughout the study, the plants received uni- blueberry cultivar, corymbosum cv 11-104. form recommended split application of 10-10-10 fertil- The experiment was set up in a randomized complete izer in May and June (Chamberlain & Barclay, Cran- block design with four treatments and six replications. bury, NJ) supplying 67 kg N/ha per year. In 2002, The four treatments were (i) control (no mulch), and fertilizer was applied at 50% above the recommended three different mulch treatments, (ii) 5.1-cm and (iii) amounts because of the lower than recommended leaf 10.2-cm cranberry fruit and (iv) 10.2-cm cranberry tissue N levels (below 1.7% leaf nitrogen) measured in leaves. Each treatment consisted of three experimental 2001 (Pritts and Hancock 1992). Overhead sprinklers plants with two border plants separating each treat- applied water as needed. Insect control and ment (plot size: 1.22 m x 6.11 m). pruning were conducted according to current prac- tices (Pritts and Hancock 1992). Mulch Plant nutrient uptake was determined by leaf analysis the first week of July in 2001 and the last week The cranberry fruit used as mulch for the experi- of July in 2002 (Pritts and Hancock 1992). Thirty leaves ment, cv 'Stevens', was har- per treatment replicate were randomly collected from vested in October 2000 by a local cranberry farmer and the 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 air away errors due to plant-to-plant variability in cane dried until brittle. Total nitrogen was determined us- number, normalizing the treatment means (Sokai and ing a dry combustion automated system Carlo Erba Rohlf 1981). In 2001, yield data was only available 1500 CNS analyzer (Fisions Instruments, Milan, Italy) from four replications. and P, K, Ca, Mg, Mn, Fe, Cu, B and Zn were analyzed Analysis of variance for changes in soil and plant by CEM microwave digestion (CFM, Matthews, NC) nutrients and weed biomass and numbers were calcu- and Thermo Jarrell Ash inductively coupled plasma lated to compare the different mulch treatments at spectrometer (Thermo Jarrell Ash Corporation, each analysis time over the two-year period. Treatment Franklin, ) (Gavlak et al. 2003). effects were tested at the 0.05 level of significance. Gen- Fruit yield (total weight) was determined by har- erally there were no significant effect of replication. vesäng ripened fruit weekly over a four-week period Means were separated using contrast statements and in 2001 (7/5,7/13,7/24,8/1) and a three-week period least significant differences (LSD, P<0.05) were used to in 2002 (6/24, 7/1, 7/9). Diseased fruit was separated determine stafistical differences between the treatment and weighed. Thirty berries were randomly selected means (SAS, Cary, ). from the non-diseased fruit to obtain a mean fresh fruit weight per berry. Results and Discussion

Soil Samples Waste Characteristics

Soil sampling was conducted in the fall and in the The analyses of cranberry fruit and leaves indicat- spring of 2001 and 2002 to determine if the mulch was ed C/N ratios of 125/1 {cranberry leaves) and 168/1 releasing any nutrients or impacting soil pH. Prior to (cranberry fruit), acidic pH (2.6 - 3.9) and TKN levels coring, n:\ulch or litter was ren:ioved from the sam- between 0.39% and 0.72% (Table 1). The cranberry pling area to prevent surface organic matter from mix- fruit mulch had a considerably lower pH and Ca and ing with the soil sample. Three cores (2.5-cm diameter Mn levels than the cranberry leaves, but higher mois- X 15~cm deep) from each treatment replicate were ture, conductivity and K levels. Due to the higher combined into a single sample and analyzed by the moisture content, cranberry fruit mulch at both appli- University of Delaware Soil Testing Program. Stan- cations rates supplied less nutrients than the cranber- dard soil tests (pH, electrical conductivity, organic ry leaves except for K (Table 1). When compared to matter analyzed by a modified Walkley-Black method other organic wastes, the wastes in this study are at and total carbon using a dry combustion automated the higher range for C/N ratio and moisture content system LECO-CNS-2000 (LECO Corp., St. Joseph, and lowest range for pH (Pickering and Shepherd Minnesota) were conducted along with, NO -N, TKN 2000, Rogers eiiï/. 2001). and Mehlich 1 extractable nutrients (P, K, Ca) Mg, Mn, The cranberry fruit in this study was still intact Zn, Cu, and Fe) analyses (Sims and Wolf 1995). and contained all its , but became mushy over time. Generally, there are no characteristics reported Weed Production in the literature describing the appearance of the mulch. However, these characteristics are important Weed production and community composition because they might affect the farm operation. In this were determined each year in August. Weeds were study, the mushy nature of the intact berries which severed at the soil surface from a randomly placed 30 rolled off the raised beds and were buoyant with rain X 30-cm area in each plot. Individual weeds were iden- made the ground difficult to maneuver and therefore tified. Weed samples were dried at 70°C for one week affected the blueberry picking. This was not the case imtil a stable weight w^as established and weed bio- for the cranberry leaf mulch. mass was determined for each weed (dry weight). As expected, the characteristics of both applied mulches, cranberry fruit and cranberry leaves Statistical Analysis (Table 1), changed during the two years of this study (Table 2). The pH of the mulch on the plots increased The fruit yield was statistically analyzed using a over time. Some nutrients (e.g., Ca, Cu) increased covariate analysis. This type of statistical analysis was most likely due to microbial degradation with release necessary due to the initial variability of established of mainly CO resulfing in increasing nutrient levels blueberry plants from bush to bush. The number of in the mulch while easy leachable nutrients such as K canes per bush was used as covariant. The covariance decreased due to leacliing. The effect of the release of helped discern between the treatments, partitioning leachable nutrients was also confirmed by decreasing

222 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.

1 application rates in Dec. Dec. 2000 Nov. 2001 Dec. 2000 Nov. 2001 Fruit 5.1 cm Fruit 10.2 cm Leaves

No. of samples 3 2 3 2 pH 2.6 3.1 3.9 3.7 C/N 168 - 125 _

Bulk density 0.684 - 0288 -- -1

Conductivity 1.98 2.58 0.36 0.74

Moisture 90 87 63 74

TKN 4800 5850 3867 7200 175 350 416 NH4'N <100 150 <100 <]00 <3.6 <7.3 <10.8 NOj- NOj-N 20 14 <10 <10 0.7 1.4 <1.1 P 1733 900 1367 900 63 126 147 K 7433 6850 1633 3100 271 542 176 S 600 550 1000 800 22 44 IOS Ca 933 1000 6700 5350 34 68 721 Mg 600 400 933 800 22 44 100 Na 100 <100 167 <100 3.6 7.3 18 Fe 1577 - 5073 3035 57 115 546 Al 1814 - 2620 976 66 132 282 Mn 39 22 156 99 1.4 2.8 17 Cu 8 3 14 6 0.3 0.6 IS Zn 16 n 39 23 0.6 1.2 42

TABLE 2. conductivity levels. The ir\crease in TKN might be Selected characteristics of cranberry fruit and leaves after caused by both, microbial degradation and immobi- application collected from experimental plots. lization of N from added fertilizer. Fruit Leaves — Oct. 2001 " — Nov,.2002 - Oct. 2001 Nov. 2002 Soil Properties and Leaf Tissue 5.1-cm 10.2-cm 5.1-cm 10.2-cm Sample no. 2 2 2 2 2 2 Some of these changes in the mulch also affected pH 4.3 3.8 5.4 5.0 5.0 4.9 the soil properties and the blueberry production. Soil c -' m z> c*111* samples for the plots mulched with cranberry fruit Conductivity 0.39 0.70 0.12 0.11 0.06 0.19 showed significant, even though small changes in t li/t /d WC soil pH over the two years (Table 3). Increased soil Moisture 50 51 53 47 25 31 - mg kg' dry wt. - pHs compared to the no-mulch treatment were TKN 7750 9150 12450 12050 4450 6500 found in Spring 2001 for the 5.1-cm fruit treatment, in NH^-N <100 200 <100 <100 500 <100 Spring 2002 for both fruit treatments and in Fall 2002 NO,- NO.^-N <10 <10 <10

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)).

ich 1 extractable nut ivienL. ricnts Conductivity OM N NH;-N NO^-N P K Ca Mg Mn ZTI Cu Fe Treatment pH mmhos/cm nn'rv» Spring 2001 No mulch 4,2 b 1,8 a 0.053 ab 0.76 a 4.1 ab 31-1 a 52.6 a 47,7 a 10-5 a 0-45 a 0.77 a 0.25 a 54.5 a 5.1-cm fruit 4.4 a 1,9 a 0.052 ab 1,01a 3,7 b 17,9 b 52,3 a 46,1 a 15.3 a 0.57 a 0.78 a 0,23 a 58.2 a 10.2-cm fruit 4.2 b 2,0 a 0,071 a 1,00a 4-0 ab 26,6 ab 53,0 a 53,3 a 13.1 a 0.48 a 0.85 a 0.27 a 68.5 a Leaves 4,4 ab 1,9 a 0,050 b 0,93 a 4,5 a 20,0 ab 42,3 b 53.7 a 13,9 a 0-53 a 0,93 a 0,62 a 58,7 a

Fall 2001 No mulch 4.3 a 0,10 a 1,9 a 0,051 a 1,29 a 3,2 a 18 9 a 49,8 a 66,8 a 18.6 a 1,17a 0,94 a 0,23 a 41,7 a 5,1-cm fruit 4.4 a 0,08 a 1,9 a 0,059 a 1,33 a 3,4 a 10.8 a 40.6 ab 68.6 a 19.4 a 0,63 a 0,89 a 0,24 a 45.9 a 10.2-cm fruil 4.3 a 0,09 a 2,0 a 0,066 a 1.37 a 3,2 a 15.2 a 41-6 ab 56-5 a 15.8 a 0,67 a 0,82 a 0,22 a 50.6 a Leaves 4,4 a 0,09 a 1.8 a 0,054 a 1,28 a 3,5 a 9,9 a 37.6 b 60,3 a 17-4 a 0,78 a 0,83 a 0,23 a 42.3 a

Spring 2002 No mulch 4,2 c 0,10 b 2.1a 0,062 a 1,86 a 2,7 a 14,8 a 43-1 b 49-4 a 13,3 b 0,58 a 0,97 a 0,20 a 41.0 a 5,1-cm fruit 4.5 b 0-09 b 2.3 a 0.065 a 1,48 ab 2,4 a 7,4 a 68,0 a 76,3 a 20,2 ab 0,85 a 1,15a 0,19 a 26.1 be 10,2-cm fruit 4,7 a 0,11 ab 1.9 a 0,053 a 1.32 b 2,5 a 11^ 80,4 a 70,5 a 20.9 a 0,83 a 1,04 a 0,19 a 20,4 c Leaves 4,4 b(: 0,15 a 1.8 a 0,054 a 1,66 ab 2,8 a 16,9 a 53.6 b 72,9 a 20,3 ab 1,2 a 0,96 a 0,19 a 32,9 ab

Fall 2002 No mulch 4.4 b 0.13 b 2,2 a 0.068 a 5.58 a 1,5 b 20.1 ab 63,5 b 88,6 a 23.0 a 0,52 b 1.17 ab 0.23 b 47.3 a 5,1-cm fruit 4,6 a 0.12 b 2,1 ab 0,062 a 6.75 a 1,9 ab 12.0 b 87,1a 104.9 a 23,6 a 0-87 b 1,57 a 0.24 ab 22,6 c 10.2-cm fruit 4.5 ab 0,15 ah 1,7 b 0,061 a 5.97 a 1,6 b 16.8 b 87,1a 78-3 a 21,3 a 0.72 b 1.12b 0.24 ab 26.1 be Leaves 4.4 b 0,18 a 1,9 ab 0-067 a 6-12 a 2,3 a 27,0 a 67-5 ab 109-4 a 27,3 a 1,65 a 1,53 a 0,28 a 36,5 ab

to 4.8. Cranberry skins contain quinic, citric and mal- [ extract) for the cranberry leaf treatment compared ic acids which might cause increased acidity. On the to the control which was also confirmed by the blue- other hand, wastes high in non-acid cations (e.g., Ca, berry tissue analysis (P < 0.05). On the other hand, in Mg) such as shade tree leaves (Heckmann and 2002, lower Fe levels (Mehlich I extract) compared to Kluchinski 2000) or poultry and pig manures and fil- the control were found in the plots mulched with ter cake (Naramabuye and Haynes 2006) might in- cranberry fruit (P < 0.05). The Fe solubility might crease the soil pH. Other mechanisms suggested for have decreased due the increased soil pH. The lower pH increase are the proton consumption capacity of Fe soil levels in the cranberry fruit treatments were humic materials present in manures and household confirmed by the leaf tissue analyses. The Fe levels in waste composts and the decarhoxylation of organic the leaf tissue of all treatments, but especially the acid anions during degradation of manures and cranberry fruit treatment are below the levels (60 plant residues (Mokolobate and Haynes 2002; ppm) recommended by Pritts and Hancock (1992). Naramabuye and Haynes 2006). Tn the current study However, leaf chlorosis, a typical sign of Fe scarcity, with surface applied mulches, the mechanisms in- was not observed. creasing the pH had a greater effect than leaching of As expected, based on the high C/N ratio of the organic acids into the soil underneath which would cranberry fruit and leaves, nitrogen in the blueberry decrease the pH. leaf analysis (% leaf N) was significantly lower In 2001, the soil nutrient analyses did not show (P=0.05) for some of the mulch treatments (Table 4). many differences between the no-mulch and the Adequate levels of leaf nitrogen in blueberry plants mulch treatments. However, more differences were range between 1.7 and 2.1% (Pritts and Hancock 1992). found in 2002 as the mulch degradation continued. Based on these levels, the first year the leaf analysis for Elevated K levels in the soil (Mehlich I extract) were all treatments show^ed low nutrient status for nitrogen found in the cranberry fruit treatments compared to (1.4% -1.5%) and in the second year, when the fertiliz- the control in 2002 (Table 3, P < 0.05) and as a result er application rates were increased, only the no-mulch elevated levels were also measured in the leaf tissue treatment was in the appropriate range. Since the leaf in these treatments (Table 4, P < 0.05). In Fall 2002, tissue samples were collected about three weeks earli- the soil analyses showed elevated Mn levels (Mehlich 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 4 Leaf 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 N P K Ca Mg S Fe Al Mn Cu Zn B ppm 2001 No mulch 1.57 a 0.13 a 0-4] a 0-25 c 0.14 c 0.13 a 42.8 a 62.6 b 23.4 c 3.7 a 11.4a 13.4 b 5.1-cm fruit 1.4] b 0.12 a 0.42 a 0.36 b 0.18 b 0.12 b 41.1a 87-9 a 43-8 b 3.9 a 14.2 B 16.4 b 10.2-cm fruit 1.42 ab 0,12 a 0.42 a 0.45 a 0.21a 0.12 b 46.5 a 90.1 a 52.8 a 3.6 a 13.1a 17-0 b Leaves 1.45 ab 0.12a 0.44 a 0.31b 0.17b 0.13 a 42.1a 74.8 ab 39.0 b 3.4 a 11.3 a 34.4 a

2002 No mulch 1.74 a 0.12 ab 0.49 a 0-42 a 0.20 b 0.13b 56-8 a 146 a 52.4 c 4.9 a 11.7 a 39.3 b 5.1-cm fruit 1.58 b 0.12 ab 0.53 a 0.47 a 0.20 b 0.12b 50.8 b 126 a 79.9 ab 3.9 a 11.6 a 47.7 b 10.2-cm fruif 1.64 ab 0.13 a 0.61 b 0-45 a 0.20 b 0.12 b 49.9 b 117 a 77.4 b 4.0 a 11.9 a 46.0 b Leaves 1.54 b 0.11b 0.51a 0.46 a 0.23 a 0.14 a 49.4 b 132 a 94.7 a 4.3 a 11.8 a 69.2 a

decrease during the growing season, the scarcity of N 3.0 in the first year is even more pronounced. The ideal C/N ratio for decomposition is 30/1 with higher ra- "a tios, as in the mulches in this study, often causing ni- 5" 2-0 N a 2001 trogen to be sequestered by the microorganisms and " 1.5 lower nitrogen availability to plants. A lower mulch 3 ES 2002 application rate (e.g., 5 - 7.5 cm cranberry leaves) S. ^"° I might increase the nitrogen levels in the blueberry 5 0.5 plant tissue. 0.0 1 No Mulch Cranberry Craníjeny Cranberry Fnjit 5.1-cm Fruit 10,2-cm Leaws Fruit Yield FIGURE 2. Average fruit size (means witliin the same year marked by the same letter are not significantly different (P < 0.05)). During the second year, a significantly lower fruit yield was determined for the mulch treatments (Figure 1). However, the average berry size was not Since the average fruit size was not different, most different (Figure 2). This reduction in yield may be likely either the bud development (e.g., due N due to several reasons. One reason might be the ob- deficiency) or pollination was affected causing a low- served nitrogen immobilization by the mulches as in- er yield in the second year. The experimental plots dicated by the tissue analysis. Another possibility is were adjacent to each other, "avoidance" of the flow- iron deficiency although this is difficult to prove af- ers by the pollinators seems less likely, unless the ter the fact. The best way to test if iron deficiency oc- quality or quantity of the nectar was altered. To better curred would be to determine if the application of fo- understand the causes of the yield reduction further liar Fe increased the yield. As discussed, leaf research should be conducted. chlorosis was not observed. Weeds 2500 Weed biomass and number of weed species were significantly lower in the mulched plots when com- a 2001 pared to the no mulch treatments (Figure 3 and 4). The a 2002 number of weed species were significantly lower in the mulched plots for both years while weed biomass was significantly different only in the second year (Figure 3 and 4). A broad leaf weed, Goldenrod, solida- Cranbeny Cranberry go spp., remained the most abundant and persistent ,1-cm Fruit 10.2-i;m Lea\es weed in each of the plots. Blueberry growers use a FIGURE 1. Fruit yield (means within the same year marked by the combination of pre-emergent , cultural same letter are not significantly different (P < 0.05)). practices (discing or mowing) and post-emergent her-

Compost Science & Utilization Autumn 2008 225 ti. Krogmann, B. f. Rogers, and S. Kumudini

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-

0 2001 tial of suppressing weeds but also of regulating soil H 2002 temperature, releasing nutrients slowly, and of con- serving organic matter and soil-water in sandy soil (Krewer 2001).

Summary and Conclusion CranberTy Cranberry Crantjerry Fruit 5,1-cm Fruit 10,2-cm Leaves This study shows that cranberry fruit and leaf FIGURE 3. Weed biomass (means within the same year marked by the same letter are not significantly different (P < 0.05)). mulches have a mixed effect on established blueberry plants. Since blueberry harvest generally involves hand picking, the cranberry fruit mulch can interfere with this process due to the juicy nature of intact fruit making the ground more difficult to maneuver. Fur- thermore, a reduced blueberry yield in the second

D2001 year and reduced nitrogen in the leaf tissue was B2002 found in both years, although the berry size was not affected. Most likely additional nitrogen fertilizer needs to be added until the mulch starts to further de- I grade and release nutrients. Another cause for the re- duced yield could be iron deficiency although this No Mulch CfBnberry Crantjerry Crantjeny Fruit 5,1-cm Fruit 10.2-cm Leaws needs to be further evaluated. On the other hand, the mulch reduced weed biomass and number of weed FIGURE 4. Number of weed species. species. The use of mulch could reduce us- age by having farmers target the more persistent bicide to control weeds. The selection of the weed species such as goldenrod. depends on the weed present. The most common pre- In conclusion, this research confirmed interactions emergent herbicide is norflurazon (solicam). Since a between soil, plant and applied mulch and showed number of herbicides are used in blueberry produc- that a novel mulch such as cranberry fruit needs to be tion, a reduction in weed species could reduce pesti- carefully analysed before being applied. The applica- cide usage by farmers by having farmers target pesti- tion of whole cranberries as mulch for established cide use to the more persistent weed species. blueberry plants is not recommended due to various Weed suppression by mulches is caused by the management problems. Instead, the cranberry fruit physical presence of the n:iaterials on the soil surface, should be crushed and composted with other wastes and/or by the action of phytotoxic compounds in (Ramirez-Perez et al., 2007). However, the increased mulches such as organic acids, ammonia, ethylene ox- pH of the compost might preclude the compost as ide, and phenolic acids (Ozores-Hampton, 1998, mulch on established blueberry plants. Due to the ease Duryea et al. 1999). However, there have been mixed of management, cranberry leaves are a better option, results concerning the beneficial effects of alternative but should be applied at a lower rate (5-7.5 cm). organic mulches. Municipal solid waste composts and paper mill sludge compost effectively sup- Acknowledgements pressed weeds (Roe et al. 1993; Ozores-Hampton et al. 1999) but beneficial effects on soil conditioning and The authors would like to thank the staff of the crop yields varied due to differences in their chemical Phillip E. Marucci Center for Cranberry and Blueberry characteristic and specific requirements of different Research for maintaining the plots and the New Jersey crops (Roe 1998). Department of Environmental Protection, Division of Cultivation and crop rotation are typically used Watershed Management, and the New Jersey Agricul- for weed control in vegetable crop production, grow- tural Experiment Station for financial support. ers of established perennial plants such as, blueber- ries, lack the option of crop rotation and cultivation is References challenging due to the narrow rows. Weed reduction practices for blueberry production include herbi- AFHA. 1985. Standard Methods for the Examination of Wa-

226 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 Health Ozores-Hampton, M. 1998. Compost as an alternative weed Association, American Water Works Association and control method. Hort. Sei., 33:938-940. Water Pollution Control Federation, , D.C. Ozores-Hampton, M. , P.J. Stofella, T.A, Bewick, D.J. Ashworth, S. and H. Harrison. 1983. Evaluation of mulches Cantliffe and T.A. Obreza. 1999. Effect of age of co-com- for use in the home garden. Hort Sei., 18:180-182. posted MSW and biosolids on weed seed germination. Bristow, K.L. 1998. The role of mulch and its architecture in Comp.Sci. Util., 7:51-57. modifying soil temperature. Aust.}. Soil Res., 26:269-280. Pickering, J.S., A.D. Kendle and P. Hadley. 1998. The suit- Duryea, M. L., R.J. English and L.A. Hermansen. 1999. A ability of composted green waste as an organic mulch: comparison of landscape mulches: Chemical, allelopath- effects on soil moisture retention and surface tempera- ic, and decomposition properties. /. 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