The Valencia discussion last month spurred some curiosity, so we decided to go one-step further with number-crunching comparisons. Using survey data from the Texas Citrus Growers League, we derived an average return per ton for each of the varieties or types of citrus in 1995-96 (Table 1) and 1996-97 (Table 2). The data represent about 20 percent of the harvest in each season, but the fact remains that these are strictly average prices, meaning that some prices were higher and some were lower than those computed here. Too, juice returns are not included for all of the tonnage reported, so the final average prices would be expected to be a little higher.
Table 1. Tons and average price per ton as determined by the Texas Citrus Growers League in 1995-96.
There are substantial differences in the average price per ton of the different orange and grapefruit varieties. However, the real measure of profitability is net return per acre, i.e., prices per ton times tons per acre. Since acreage was not reported to the League, we cannot calculate returns per acre.
What we can do is calculate the relative tons per acre of one variety that would be required to equal the returns of another variety, based on the respective prices of each. These calculations are shown in Table 3 as the number of tons per acre of each of the other varieties which would be required to equal the returns per ton of Valencia oranges produced in each of the two seasons.
Table 3. Tons per acre of other citrus required to equal the returns per ton of Valencia oranges.
Obviously, all but navel oranges required the production of more tons per acre to equal the Valencia returns per acre during the two seasons for which we have data. Looked at another way, if you produced 22 tons per acre of Rio Red grapefruit in either season at these average prices, you would have received the same total dollars from a production of 11.4 tons per acre of Valencia.
The principles of these calculations are not limited to Valenciasyou can do the same comparisons for any two varieties. Simply divide the average price per ton of one variety by the average price per ton of another variety to determine how many tons of the second variety are needed to equal one ton of the first. For example, in 1995-96, it would have taken 1.58 tons of Rios to equal the returns from 1.0 ton of Marrs/EO, whereas in 1996-97, it would have taken only 1.07 tons of Rios to equal a ton of Marrs/EO.
WATER SITUATION CRITICAL-
As May ends, the water level in each of the reservoirs stands more than 50 feet below conservation level. Too, the U.S. share of water has now dropped below 30 percent, with Cindy Martinez, Watermaster, predicting that to decline to about 22 percent by the end of July.
There should be some reduction in irrigation demand in Junemelon and cantaloupe harvests are in progress, sorghum irrigation should be finished (for those who irrigated it) and much of the corn and soybeans are close to final watering. That leaves cane, cotton, citrus and pastures to be irrigated into the summer. Then, August sees the startup of fall vegetables and corn.
Obviously, if the situation does not improve, the proposed fall crop plantings will be reduced substantially. A band of thunderstorms moved through west Texas at mid-week, but there does not appear much likelihood that any significant inflows resulted from those storms. So, the Valley has now gone three months plus since the last significant rainfall in February. About the only positive note is that with each day that passes, we are one more day closer to the day that it will rain again
METERED WATER IN CITRUS-
As you know, most water districts calculate an average irrigation for all crops and acres based upon total volume pumped divided by total acres irrigated. As such, about everyone considers an irrigation to be at least 6 inches or more of water. I have long contended that citrus uses far less water per irrigation, partly because of non-tillage which allows faster irrigation and partly because citrus orchards rarely have runoff of tail water as commonly occurs in row crops.
Last year, we began to see evidence that my contention is correct. Full border-to-border irrigations with water meters were taking just over 4.0 inches of waterbefore the rains started. This season, more groves are using metered water. Bill Friend, manager of La Feria Irrigation District, tells me that metered irrigations in citrus this spring are running between 4 and 5 inches. For comparison, the La Feria Irrigation District average irrigation was 0.62 foot, i.e. 7.49 inches.
Some have claimed that citrus is a major water user, with four to six irrigations in a normal year (when supplies were plentiful)but that obviously is not the case. And it does feel good to be proven right after all these years when citrus irrigation was using little more than half the district average.
ALTERNATE FURROW IRRIGATION IN ROW CROPS-
I have also long contended that row crops, because of their relatively shallow root systems, could be more efficiently irrigated using alternate furrows. Alternate furrow irrigation, especially in conjunction with poly pipe (or gated pipe) and surge flow values, should reduce deep percolation loss, should reduce tail water loss and could probably be carried out with only 60 to 70 percent s much water. Believe it or not, several fields in western Cameron County are being irrigated in alternate middles. Some of those are being metered, and it would be interesting to compare those to full irrigations to get a better idea of just how much water can be saved by alternate furrow irrigation in row crops.
There has been research on alternate-furrow irrigation, including that on sorghum by Leon New in Texas, back in the 60's and 70's. Generally, those trials showed equal yields with barely more than half as much water on maize, sorghum, cotton, potatoes, sugar beets and soybeans; those which resulted in slightly lower yields were considered acceptable for the amount of water that was used.
That is not to say that alternate-furrows irrigation will work on all soils and crops in the Valleythat can best be determined by trial, which a number of growers are doing. Presumably, there could be problems with extremely long irrigation runs and with the wider rows common to cane and melons. Again, it has to be tested.
The prospect of being able to save even 40 percent of the available irrigation allocation is something to consider.
The smoke-haze from all the wildfires in southern Mexico and Central America has been around for 4 weeks with only a couple of days of clear skies since it started in early May. The media, more than anyone, have been asking about the effects on agricultural crops in the Valley (and elsewhere).
While I havent seen any actual measurements of the reduction in daily light intensity, obviously total sunlight has been reduced. Nonetheless, we normally receive far more daily sunlight than needed for citrus, so I cannot imagine a negative effect of the haze on citrus.
Apparently, the haze has kept temperatures down a little and has boosted humidity. Generally, both lower temperature and high humidity should result in lower evapotranspiration, i.e., less water loss from the soil surface and from the leaves.
So, while I am not concerned about the effects on citrus groves, I would just as soon see it clear outmaybe then we could get a weather pattern that is more favorable to rain.
The basic fruit drop periods are over, so next years crop is set. Excepting navels, any incidental drop between now and harvest will be offset by increased size.
The problem is waterfor proper fruit sizing, water is essential; otherwise fruit development suffers as the tree uses water stored in the fruit. Have you ever noticed an orchard that is being clean pickedtrees yet to be harvested look normal but those picked a couple of days previously look wilted? Basically, the trees were taking water from the fruit by day and replacing it at night, so everything looked normal.
f I had only one irrigation left, I would push the trees to the point of afternoon wilting before using the water. With two irrigations, I might use the first one before that time.
One precaution that you should have figured out for yourself: just because you have an allocation does not necessarily mean that the water will still be there when you want it. After all, if the well goes dry, it goes dry.
CITRUS PEST UPDATE-
A few groves have rust mite populations but overall they remain at low levels due to the very dry spring in which no significant rainfall has fallen since early February. Some groves have required treatment for rust mite populations and armored scale due to the mild winter. Melanose and greasy spot are quite high in many groves with applications of copper this spring necessary in many groves to keep these problems down to a minimum.
The extremely dry spring has worsened the water crisis that has severely affected south Texas for the last four years. With no spring rains, the irrigation has brought the water level at the Falcon Reservoir to a low of 250 feet above sea level which is nearing the all time low of 249 feet in August of 1996. With summer approaching, traditionally the driest period, pest control decisions will be more difficult than in past seasons because quality and size may be impacted.
JULIAN W. SAULS, Ph.D.