Using Fish Waste Hydrolysates as a 

 Fertilizer for Apples and Blueberries 



Sarah A. Weis and William J. Bramlage 



Department of Plant and Soil Sciences, University of Massachusetts 



New England processing plants generate up 

 to 100 million pounds of fish waste per year. 

 Much of this material is disposed of at sea and in 

 landfills, practices that can be both offensive 

 and wasteful. Procedures have been developed 

 to liquefy fish waste as stable acid hydrolysates 

 containing specified percentages of nitrogen (N), 

 and other elements. These hydrolysates have 

 been tested as fertilizer sources for greenhouse 

 crops, turf grasses, and cranberry bogs, with 

 encouraging results. 



Nitrogen is the primary fertilizer element 

 used for fruit crops. The availability of fish 

 waste hydrolysates for use on fruit crops offers 

 an alternative to conventional fertilizer sources 

 that also may be beneficial to the fishing indus- 

 try, waste disposal problems, and concerns 

 about environmental contamination. Further- 

 more, its use might be especially appealing to 

 the increasing numbers of people interested in 

 growing crops as organically as possible, since 

 the hydrolysates provide N in an organic form. 



In cooperation with the University of Massa- 

 chusetts Gloucester Marine Station, we under- 

 took a program to test the use of fish hydroly- 

 sates as a fertilizer source for young apple trees 

 in 1990 and 1991,andalsoforhighbushblueber- 

 ries in 1991. 



Experiment 1 



We selected a block of one-year-old Early 

 Red One Delicious apple trees on Mark root- 

 stock, planted at the University of Massachu- 

 setts Horticultural Research Center (HRC) in 

 Belchertown. These trees were being grown 

 using standard horticultural practices except 

 for the fertilizer treatments described below. 



Fish hydrolysates used as fertilizer were 

 prepared by personnel at the University of Mas- 



sachusetts Marine Station, Gloucester. Each 

 type of hydrolysate was prepared to contain 

 2.5% N, 5% P, and 2.5% K, and they also con- 

 tained small amounts of other mineral nutri- 

 ents. 



Treatments were as follows: 



1. Ammonium nitrate, 0.1 lb N per tree. 



2. Herring hydrolysate, 2 qt per tree. 



3. Cod hydrolysate, 2 qt per tree. 



Treatments were replicated 6 times, with 

 individual trees as experimental units. Each 

 treatment applied the same amount of N per 

 tree, but treatment 1 did not provide the P and 

 K that was contained in the fish hydrolysates. 

 These treatments were applied in both 1990 and 

 1991, and fertilizers were applied on May 29, 

 1990 and May 7, 1991. Tree growth was mea- 

 sured by recording trunk diameter at an indi- 

 cated height in May and September, 1990, and 

 October, 1991. Leaves were taken for mineral 

 analyses in September, 1990, and in July, 1991. 

 In October, 1991, the limited numbers of fruit on 

 each tree were harvested. They were stored for 

 6 months at 32°F plus 1 week at 70°F, and 

 occurrences of bitter pit, senescent breakdown, 

 and rot were recorded. 



Concentrations of N, P, and K in the leaves 

 are shown in Table 1. In 1990 the only difference 

 was in K, with the fish hydrolysates (which 

 contained 2.5% K) producing higher leaf K con- 

 centrations. In 1991, there was higher leaf N 

 when cod rather than herring hydrolysate was 

 used, and higher leaf P when herring rather 

 than cod was used. Since, however, both hydro- 

 lysates were made up to provide the same 

 amounts of N, P, and K, these differences have 

 no apparent association with treatment. Leaves 

 were also measured for calcium, magnesium, 



Fruit Notes, Summer, 1992 



15 



