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Crop storability and shelf life

In many cases, perhaps even in most cases, when we observe poor crop storability, the cause is inadequate calcium in the cell membranes. Elevated calcium levels within the stored crop cell membranes provides membrane strength, and prevents the cells from leaking sugars and nutrients, which sets the stage for decay and spoiling.

Chip potatoes without adequate calcium are a good illustration. When the cell membranes do not contain adequate calcium, the cells leak sugars which settle to whichever part of the potato is the lowest, following gravity. When these potatoes are sliced and fried, the accumulated sugars burn, producing a black edge on the chip. When you fix the calcium supply problem during the fruit cell division stage, storability problems are greatly reduced or eliminated.

2020-03-16T14:04:36-05:00February 21st, 2020|Tags: , |

Using boron to speed up natural maturity and senescence

One of the characteristics boron is known for is to facilitate rapid nutrient transport to the sugar sinks. This effect can be very valuable to speed up crop maturity and senescence while also increasing harvest quality.

When an alfalfa crop is growing rapidly and still very vegetative in late fall as we approach winter dormancy it is possible to quickly trigger senescence and rapidly move the sugars contained in the plant down into the crown with a generous foliar application of boron. A treated section can turn brown within a few days to a week (depending on weather and time of year), as all the sugars move down into the crown and the plants begin to senesce. The following spring, the section treated with boron in the fall will emerge from winter dormancy much faster and with many more shoots than an untreated section, because the crowns have much more energy from the stored sugars. Any perennial crop with a similar growth pattern will show this effect. 

This effect can also be used to speed up the natural maturity process of other crops. A generous foliar application of boron on fruit such as tomatoes or apples will speed up the natural sugar transport into the fruit. This can help the fruit color and mature quickly and evenly days to weeks earlier than plants without a generous supply of boron.

This effect of boron on speeding up maturity and natural ripening can also be used on small grains in place of a desiccant or harvesting aid. Wheat that receives a foliar application of boron can mature rapidly and dry down as much as five to ten days faster than plants without adequate boron. The upside is that there is often a gain in test wheat and protein content, since boron produces this effect by increasing photosynthate and protein transport into the grain rather than reducing transport to the grain as a desiccant might.

Boron does not produce these effects if the crop is not at the right stage of growth. It can only speed up the plant processes which are occurring naturally. Managed well, boron applications can speed up these natural processes dramatically, and produce a higher quality grain or fruit, with an improved nutritional content.

How much boron is required? It varies based on the existing boron content of the soil and the crop. Many crops and soils are deficient, which is why crops are not maturing well in the first place. Often, the upper end of label rates are required if this is the only application being applied in the season. It is better to supply the crops foundational boron requirements during the growing season, and then top off the requirements with a lighter application a few weeks before maturity to produce the optimal effects we are looking for. 

2020-03-16T14:00:31-05:00February 6th, 2020|Tags: , , , , |

When nutrient applications cost yield 

Contemporary agronomy and plant nutrition management has been framed primarily around the Law of the Minimum: the nutrient with the most limited supply will determine the maximum possible crop yield. 

In practical application, we measure the nutrient concentrations that are present, either in soils or plants, and add what is missing or low. 

The Law of the Minimum paradigm is commonly misapplied with two gigantic gaps in thinking. 

This paradigm is often applied selectively to some nutrients. It may be applied to nitrogen, phosphorus, and potassium, but not to zinc, copper, manganese, cobalt, and molybdenum.

It is also common to apply this paradigm with no consideration for the opposing perspective, the Law of the Maximum. The law of the maximum states: the nutrients which are present in excess limit crops to the highest level of the nutrients that are antagonized by the excess.   

When we first started using sap analysis on a large scale, it quickly became apparent the law of the Maximum is often missed.

It is often the excess of the nutrients the grower applies, which causes deficiencies of other nutrients, that limits plant health and overall yield potential. 

Excessive nitrogen and potassium at the wrong stage of development cost yield on many farms, because of other nutrient deficiencies that are created by the excess.

 

2020-03-16T13:55:45-05:00January 17th, 2020|Tags: , |

The essential nutrients needed to increase photosynthesis

Most commercial crops are photosynthesizing at only a fraction of their inherent capacity. The limiting factors that keep them from reaching their potential are most commonly inadequate water, carbon dioxide, not enough manganese, not enough chlorophyll, and too high leaf temperature. 

Water is obvious. The solutions to infiltrating and retaining large volumes of water in our soil profiles to produce drought proofed soils are known and will be described more in the future.

Carbon dioxide as a limiting factor is often not considered as it should be. The most important reason to have high organic matter content soil is so we can lose the organic matter as CO2 while we have a green plant to capture it. In crops that are efficient photosynthesizers such as a perennial polyculture of well managed grazed forages, corn, sugarcane, and many others, carbon dioxide levels can be depleted in the local air to less than 100 ppm by mid-morning on a warm day. For the rest of that day, photosynthesis is limited by CO2 supply. 

Manganese is needed for water hydrolysis. When water is absorbed from the soil and moves up into the leaf, the first step before water can participate in photosynthesis is that the H2O molecule is split to H and OH ions, hydrogen and hydroxyl. This water splitting process is called water hydrolysis and is completely dependent on manganese. Even when you have perfect environmental growing conditions, perfect water, temperature, sunlight, and carbon dioxide, if the plant does not have abundant manganese, photosynthesis will be slowed.

Chlorophyll levels can often be increased by making sure that plants have adequate levels of magnesium, iron, and nitrogen. Nitrogen is seldom low because it is one of the nutrients much used to cover up other imbalances, and is frequently over-applied. Magnesium is easy to correct with a foliar application, and also frequently low. Iron is almost universally low in plants, contrary to most soil and plant tissue analysis reports, because the (oxidized) form of iron reported on these assays is not physiologically active in plants. Any of these three nutrients can be used to quickly give plants a dark green color by increasing chlorophyll. Since nitrogen is generally abundant, magnesium and iron usually produce the biggest economic crop response. Leaf sap analysis can identify precisely what is needed.

When leaf temperatures are too high, photorespiration becomes dominant instead of photosynthesis, and plant energy levels begin dropping, ammonium is produced in leaf tissue as a result of protein catabolism, and plant immunity is quickly reduced. There is not a direct correlation between leaf temperature and air temperature. Healthier plants remain cooler for much longer at higher leaf temperatures, through a variety of mechanisms.

Look for more detail on each of these in future posts. 

 

2020-03-16T13:54:54-05:00January 15th, 2020|Tags: , , |

Foliar feeding of plant nutrients

I have long been an advocate of foliar feeding nutrients as one of the most financially rewarding applications that can be made to a crop, and the practice has become mainstream in many regions. 

Thus, it comes as a surprise that in some areas growers still consider foliars to be an ineffective tool. I would suggest they are ineffective only when they are not properly designed and applied. 

Some of the first published papers on foliar feeding I have read were based on research conducted for the Atomic Energy Commission by Sylvan H Wittwer and Harold B Tukey in the late ‘40s and ‘50s. Their congressional testimony is as relevant and exciting today as when it was first published. (Approximately 1952?)

I cleaned up the document and made some slight edits to make it more readable, but kept all the underlining in the original report. You can read the 24 page report (and bibliography) here. You will find valuable and intriguing information. Here are some excerpts:

  • not only can plants absorb nutrients through the roots, but also through the foliage, the fruit, the twigs, the trunk, and even the flowers.
  • the most exciting news is the foliage feeding of plant—that plants can take up nutrients through the foliage. Here is a case where the farmer has really gotten ahead of the scientist as so often happens. He has learned that foliage feeding is helpful and he has adopted the practice. 
  • The first point I should like to make is that the materials do enter the leaves rather easily.
  • In the final analysis, we find that a leaf is a very efficient organ of absorption. We find that the materials move into the upper surface of the leaf as well as the lower surface. We find that it enters at night and during the daytime. Further, we find the leaf surface of a 12-year-old apple tree in Washington State to be equivalent to one-tenth of an acre, even though that tree only occupies about one-hundredth of an acre. So there is a large feeding area.
  • Not only do these materials enter rather easily—and this is interesting, too, because all the textbooks used to tell how the plant was covered by an impervious cuticle—now we find textbooks are re-written and the leaf is reported as a beautiful mechanism for absorption. 
  • If we apply it to the leaf we find it moves downward through the plant—at the rate of a foot an hour. It is very interesting that it moves so freely. If we apply it to a middle leaf it moves both ways very effectively.
  • We have seen that materials are absorbed by the plant and move rather freely in the plant. The amounts may at first seem relatively small, but to off set this handicap, the efficiency is high. In fact, this is the most efficient method of applying fertilizer to plants that we have yet discovered. If we apply these materials to the leaves in soluble forms, as much as 95 percent of what is applied may be used by the plant. If we apply a similar amount to the soil, we find about 10 percent of it to be used. 
  • For example, the soil may be cool and low in phosphorus at just the time it is needed by a transparent vegetable or strawberry plant. Or there are cases where the soil locks up certain materials that are applied, like potash and magnesium. Under such conditions we find leaf application very significant and very effective.
  • But now we are highly suspicious that here may be a case where materials are actually being leached out of the leaves maybe by overhead irrigation, maybe by rain, and having a profound effect upon the crop.  

 


2020-03-16T13:44:48-05:00December 20th, 2019|Tags: , , |

How to Propagate Aphids

It is important to propagate aphids in our fields so the beneficial insects such as lady beetles have something to feed on. It is quite easy to produce a tremendous aphid population which can sustain a large number of beneficials and not be negatively impacted. We just need to give them the right environment.

Here are the easy steps to produce an optimal environment for aphids, which require free nitrates in the plant sap.

Step one, apply more nitrogen then the plants can utilize at the current growth stage.

Step two, do not supply magnesium for better photosynthesis.

Step three, do not apply sulfur the plants needs to produce sulfur-bearing amino acids and complete proteins.

Step four, do not supply molybdenum for the nitrate reductase enzyme.

Step five, do not apply any boron that might boost plant immunity.

If you follow these five very simple steps, you can be sure that your crop will provide the perfect food source for aphids. In addition, it will also be the optimal food source for many other larval insects such as corn rootworm, earworm, corn borer, cabbage looper, tomato hornworm, and others. Really for any larvae. Propagating these larvae provides a ready food source for songbirds and beneficial insects, a valuable ecosystem service.

Of course, if you do not desire to propagate these insects on your crops, the solution is obvious. Do the reverse of the five easy steps, and these insects will not be able to use your plants as a food source.

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