By Dr. Stephen Williams
CitriNews: December 2002 Vol. 5, Iss. 3; Citrus Research and Education Institute
From November 2002 growers will no longer be paid for their oranges according to weight (the contract box system) but a new system that takes into account the quality and well as the quantity of the fruit. This is the pound solid system of payment. Since the system was introduced in Florida, the average quality of the juice produced by that State has improved dramatically - the system encouraging everyone in the industry to think ‘quality’ rather than just ‘quantity’. It is anticipated that Belize will have the same experience. This article highlights what the new payment system will mean to growers and provides some ideas of what growers can do to ensure that they get paid the best price possible for their oranges.
1. What are pound solids?
In simple terms, pound-solids refers to the weight of sugar present in the citrus juice. In the factory lab, first the amount of juice in a box is determined and then, by brix, the percentage of sugar in the juice is determined. This data is then used to calculate the amount of pound solids per 90 lb box of oranges.
2. How will growers know how much they will get paid? Figure 1 shows where growers should look on their scale ticket for the indication of the pound solid content in their fruit. From November 2002, this is the figure that will be used to determine how much growers will get paid for their fruit. The price paid for fruit delivered to the factory will not be dependent only on the number of boxes but on the number of pound solids in those boxes of orange. The pound solids for the load are then calculated as shown.
Figure 1: Where to look on your scale ticket to find out how many pound solids are in each box of oranges delivered to the factory. This grower had 4.85 pound solids per box.
An example of how payment to growers will vary depending on the pound solid content of their fruit can be seen in Table 1. The pound solids (ps) of Grower 1 was measured in the pound solid laboratory as 4.20 ps / box while that for Grower 4 was found to be 7.20 ps / box of fruit. This difference in pound solids per box will make a big difference in what the grower will get paid under the pound solid system. The current estimated final price (as of October 2002) that will be paid to growers is $1.02 per pound solid, so Grower 1 will get paid $428.40 for his load of fruit while Grower 4 will get paid $734.40 for his load of fruit. Under the ‘old box system’ all these growers would have been paid an industry average of $572 for their 100 box load of fruit. In reality, the pound solid for most growers will be somewhere in between these two extremes. Growers can look on last year’s scale tickets for an indication of how many pound solids were in the fruit they delivered to the factory. If you do not have your scale tickets from last year, CGA has this information and can provide it to you on request – this will give you a guide as to the pound solids content of your fruit last year.
Table 1: Four growers, each deliver 100 boxes of fruit to the factory – how much will they get paid under the pound solid system? Calculations based on payment of $1.02 per pound solid which is equivalent to $5.72 per box under the ‘old’ box payment system.
3. How many pound solids should I expect in each box of fruit?
For the 2001/2002 crop year, the average pound solid production for the Belize citrus growers was 5.64 ps / box. Some growers in Belize produced fruit with less than 4 ps per box while other produced fruit with more than 7 ps / box. In Florida, the average is 6.5 ps/ box. The pound solids you can expect from your fruit will depend on variety, rootstock, soil type, age of tree, the level of grove management and the timing of harvest.
Figure 2: Ten year average pound solid and box yields for Valencia orange in South West Florida. Data obtained from 65 blocks covering 4,000 acres. Data adapted from paper by Fritz Roka and Robert Rouse, Southwest Florida Research and Education Center, ,Ronald Muraro, Citrus Research and Education Center, Tracking Citrus Yields in South West Florida.
Data from Valencia trees growing in Florida provide an indication of what pound solid yields growers in Belize should aim for (Figure 2). Pound solids production in younger trees will be lower than in older trees. Growers in Florida with a well managed grove of Valencia may expect around 3.41 ps / box, three years after planting and as high as 6.31 by year 10. These figures give growers in Belize an idea of targets for them to aim for. CREI will be collecting data from Belize so that we can determine how many pound solids can be reasonably expected from which soils types and which rootstocks in Belize.
4. Why are pound solids per acre more important than pound solids per box?
Growers are now becoming familiar with the term pound solids per box. But, in fact, information on the pound solids per acre will give growers a better indication of how productive their grove is. The data in Table 2, explains this in more detail. Groves that have low yields often have high pound solids per box, but the total pound solid produced for one acre will be low. For example, growers who produce fruit with high pound solids of 6.5 ps / box but have low production of 50 boxes per acre will have less total pound solids (325 ps / acre) than a grower with only 4.0 ps / box but producing 300 boxes per acre (1200 ps / acre) (Table 2). Growers should determine and monitor yearly changes in pound solids per acre if they are to maximize their income, aiming for high pound solids (above 5.5) and high yields per acre (above 200 boxes per acre), that is above 1,100 ps / acre. Figure 2 reveals that in Florida 7 to 10 year old Valencia trees average around 2,500 ps / acre. This is what growers in Belize should aim for!
Table 2: Comparing pound solids per acre for citrus groves with varying levels of production and pound solids per box. Low yielding groves tend to produce fruit with high pound solids per box, but in terms of pound solids per acre, overall pound solid production in such groves will be unacceptable.
5. What do growers need to do to get maximum payment for their fruit?
Rootstock selection and soil type are the most significant factors that influence pound solid production. CREI will be dealing with these issues in greater detail in a subsequent issue of CitriNews. In an established grove, however, there are five main activities that growers need to focus on to increase pound solid production in their fruit: (i) apply lime, (ii) fertilize, (iii) control weeds, (iv) control greasy spot, and (v) harvest at the correct time. The first four issues must be dealt with if growers are to increase pound solids in their fruit, but are dealt with briefly here as they refer to longer-term grove management activities and are dealt with in more detail in other CREI publications. The fifth issue, harvest at the correct time, is dealt with in more detail here as this is something that growers can focus on right now (December 2002) to increase pound solid production in their oranges.
(i) Apply lime. Make sure the pH of your soil is between 5.5 and 6.0. CREI can test your soil samples for pH and provide a recommendation on how much liming material you should add to your grove to get the correct pH. Testing your soil pH only costs $1 for 20 acres. Correct soil pH is essential if the soil nutrients are to be taken up by the citrus tree. Without the correct soil pH the nutrients will just remain in the soil and do not move into the tree.
(ii) Fertilize. Make sure that you add the correct amount of fertilizer to get optimum pound solid per acre. Ask CREI staff about testing your soil and leaf to determine how much fertilizer you need to add to get optimum production. Growers should get their soil tested every 2 to 3 years ($37 for each 20 acres) and leaves analyzed every year ($45.20 for each 20 acres). Normally, two applications of granular fertilizer should be applied each year. The first in November / December, before the onset of the flower flush, and the second in May / June, at the start of the rainy season, just before the second flower flush.
(iii) Control Weeds. Weeds will compete with the citrus tree for nutrients and thus reduce your overall fruit production.
(iv) Control Greasy Spot. Pound Solids is a measure of the amount of sugar in your fruit. Sugar is produced by the leaves, so without sufficient leaf the sugar content in the fruit will be low and pound solid production per acre will be low. Greasy spot leads to leaf loss and thus will significantly affect the tree's ability to produce sufficient sugars to produce fruit with high pound solids - on a per acre basis. Trees with high levels of greasy-spot infestation will have low yields and may well produce fruit with high pound solids / box, but pound solids production per acre will be low. Greasy-spot should be controlled by making at least two applications of copper fungicide (4lbs / acre) per year to protect the leaf flushes that occur in January/March and in June. The protection of the June flush should be made in July / August and can be combined with an application of citrus spray oil (5 gals /acre) with the copper fungicide. Contact CREI for further information.
(v) Harvest Fruit at the Right Time. This is probably the most significant thing that growers can do right now - make sure you harvest each crop of fruit on your tree at the right time for the best pound solids. Figure 3 shows the average weekly variation in pound solids, degree brix and ratio for fruit delivered to the factories during the 2001/2002 crop year here in Belize. Based on data from last year's crop, you will notice that, on average, first crop fruits harvested at the end of January contained higher pound solids than fruit harvested at the end of December and, on average, second crop fruits harvested in April and May had higher pound solids compared to second crop fruits harvested in early March. It is important to note that this data reflects the time of average pound solid production for the whole industry, and growers should use this information as a guide only and not use it as an indication of exactly when the fruit in their grove will achieve maximum pound solids. But generally it can be said that if fruits are harvested too early (even if the ratio is 13:1) they may have lower pound solids. What is termed as 'early' will be different for different groves, varying from farm to farm and from year to year, depending on grove location, inputs and weather patterns. Thus, fruit that has merely 'passed' the minimum ratio requirements of 13:1 does not necessarily have the optimum pound solids. Figure 3 shows how in early March the average second crop ratio for the industry was 14.95 and 15.53, high enough to warrant delivery to the factory, but the average pound solids per box for the industry was relatively low - 4.87 and 5.02. It was not until April and May that the average pound solids per box for the industry reached above 6.00.
Figure 3: Weekly variation in pound solids, (acid:brix) ratio and degree brix for orange delivered to the factories in Belize during the 2001/2002 crop year.
So, what does this data tell us about deciding on the best time to harvest orange?
It tells us that growers should...
1. Wait until the fruit is fully mature - that is, it achieves ratio 13:1 or greater - take 6 to 10 representative fruit from your grove to get tested at the factory lab.
2. Once the fruit is mature (reaches ratio 13:1), wait for further increases in the fruit's pound solid content. The data suggests that the fruit should achieve the highest pound solids two to four weeks after the fruit reaches maturity. This may vary between the first and second crop. As the second crop is gaining pound solids during the dry season, growers will need to monitor it closely to ensure that they do not leave the fruit on the tree too long so that the fruit dries out. If the fruit is allowed to dryout, the pound solids will become lower. Additionally, for the second crop, once it reaches maturity (achieves ratio 13:1), it will achieve maximum pound solids more quickly than the first crop.
3. Monitor Brix. These suggested periods for increased pound solids are for guidance only. It is important to monitor brix and juice content for your fruit on your farm. Keep an eye on your fruit and make sure that it is not drying out as fruit with high brix but low juice will have low pound solids. If the Brix for your fruit is around 11.00 to 11.50 or above (and the fruit is juicy), this indicates that the pound solids in your fruit is high. However, growers should also note that early varieties of orange and Valencia on Volka rootstock (especially in young groves) may never achieve high brix or exceed 5.0 ps/ box. Such fruit should be harvested as soon as it reaches maturity. Generally, as long as the fruit is not drying out, as the brix increases so does the pound solid content. Figure 4 shows how average pound solid per box increases as the brix category value increases. This data can only be used as a guide and should not be taken to reflect the exact relationship between pound solid / box and brix on your farm. Pound solid per box for fruit at a certain brix will vary from grower to grower and from grove to grove. If growers wish to purchase their own refractomer (the equipment required to measure brix), a hand-held model, suitable for testing in the field, can be obtained for around Bz$300. Contact CREI for more information.
Figure 4: Average pound solids for second crop fruit of increasing 0.5 unit Brix categories, for the crop year 2001/2002. Note that there is a high level of variation for actual pound solid values for each load of fruit in each category of brix. Thus, these figures should be used a guide to possible pound solid values that could be expected at a certain brix and not as absolute values.
4. If necessary, get the pound solids lab to determine the pound solids content of the fruit before harvest. If you want to do a more detailed check of your pound solids, the pound solids lab at the factory can do it for you. Check with the pound solids lab beforehand to make sure that they have time to schedule a test for you. It may be difficult for them to do so during the peak of the season, but they will do their best to accommodate your needs. To get your fruit tested, you will need to collect about 45 lb (about half a box) of fruit. The fruit must be representative of your grove. That is, do not take all of the samples from one tree, take fruit throughout the grove and do not pick only the best looking fruit - pick a range of fruit types that will represent the whole load that you intend to send to the factory. Growers should be mindful of the fact that the determination of pound solids per box of fruit will be highly dependent on how the fruit is sampled.
5.Harvest first and second crops separately. This is very important! Mixing first and second crops will reduce the total pound solids in your load. Both first and second crops will reach maximum pound solids at different times and so the decision of when to harvest each should be made separately.
Growers should also note that...
A. Small-scale growers, because of the relative small size of their crop - will be in the best position to take advantage of the pound solid system, by harvesting at the optimum time. They should take advantage of being able to deliver their fruit to the factory once the brix reaches above 11.5. It is still vital, however, that small-scale growers contact the factory's 'fruit logistics office', or CGA to schedule a time for fruit delivery. This must be done before harvesting the fruit. If you do not have a schedule for delivering your fruit to the factory, your fruit will probably have to wait in a queue. Fruit that is in the queue too long will deteriorate losing pound solids and losing money.
B. Large-scale growers will need to schedule fruit delivery to the factory over time. It is extremely important that growers schedule fruit harvesting and delivery to the factory in agreement with the 'fruit logistics office'. Large-scale growers will need to start harvesting their fruit as soon as possible, after it reaches the 13:1 ratio. If they wait until the fruit reaches optimum pound solids they are unlikely to get all their fruit into the factory on time. Large-scale growers should monitor changes in degree brix and juice content and if the 'fruit logistics officer' is kept informed of progress he will do his best to accommodate delivery of as much high pound solid of your fruit to the factory as is possible. Large-scale growers should be aware; however, that factory logistics will not allow growers to deliver all of their fruit to the factory at the same time. Growers should bear this in mind when obtaining a schedule for delivery - assessing the size of their crop and the capacity of the factory.
6. And Finally...
If all in the Belize citrus industry work together to increase the average pound solids from the current 5.64 to the Florida average of 6.5, at current levels of production (4.1 million boxes) and current international citrus prices (around US$1 per pound solid), this would mean an additional US$3.5 million to the industry - 60% of which would be paid directly to growers. Thus, growers who make sure that their fruit is delivered to the factory with the highest possible pound solids will benefit themselves and the industry.