In the past I have had many conversations with growers about plant nutrition in their high tunnels. A good plant nutrient management plan is an integral part of making a success of the crop you are growing. Plant nutrition is important to grow a strong and healthy seedling, the first step of a successful crop. Fertility management of especially vining crops (e.g. tomato, cucumber, peppers) are critical to achieving a good yield. It does not matter if you grow your crop in soil or in a soilless production system. Steering your crop to have the optimum balance between vegetative and reproductive growth will result in good yields over a longer period. It is important for growers to know what is in their water and soil. Therefore, soil analysis of a representative sample of the area that will be planted, and water analysis of a water sample from the source that[Read More…]
28 articles tagged "Soil Fertility and Fertilizers".
We can never emphasize too much the importance of conducting soil tests. Ideally, soil test should be conducted on a yearly basis. The reason soil testing is so important is because it provides information about the nutrient composition of the soil so that growers will know how much fertilizer to apply for the following season. In addition, soil tests enables farmers to find out if there are concerns, such as pH, salinity etc. If these factors are off track, we might be able to address the problems before planting. In most cases, addressing the problems before planting is more efficient and cost effective than during the season. Purdue Agronomy Extension provides a list of laboratories that offer soil test services https://ag.purdue.edu/agry/extension/pages/soil_testing.aspx I will use the A&L Great Lakes Lab as an example, explaining how to use this service. A&L Great Lakes laboratories provide seven (S1 to S7) soil test packages.[Read More…]
We have grown strawberries from Aug, 2015 to May, 2016 in one of our high tunnels at Southwest Purdue Agricultural Center. After taking the strawberry plants out of the high tunnel in the end of May, we did have enough time to grow a warm-season crop, like cucumbers. However, because for most of us June is such a busy time working in the field, we decided to put cover crops inside the high tunnel in the summer months and plant cool-season crops in the fall. Our primary goal of growing cover crops is to provide nitrogen for the following crops and increase soil organic matter. We decided to use a legume cover crop cowpea in this case because it has excellent drought and heat tolerance. Cowpea at a rate of 100 lbs per acre was sowed on June 17th. With the high temperatures inside the high tunnel, cowpea reached 30’’ high[Read More…]
We sometimes hear that excessive nitrogen could delay fruit set, stimulate excessive vine growth, and depress overall yield of pumpkins, but it is often unclear how much nitrogen is too much. This article reviews research on nitrogen fertilizer rates for pumpkins, and discusses the potential factors that might affect the recommended nitrogen rate. In a study conducted in 1987 and 1988 in Kilbourne, IL, four nitrogen rates were compared: 50, 100, 150 and 175 lb N/acre. The first three rates (50, 100 and 150 lb N/acre) were applied through fertigation, while the highest rate (175 lb N/acre) was applied preplant and about a month after seeding. The study found the highest early and total marketable yields were obtained with fertigation of 100 lb N/acre. The lowest total yield was associated with the lowest nitrogen rate (50 lb N/acre). Fertigation with 150 lb N/acre and dry-blend with 175 lb N/acre delayed[Read More…]
In a recent visit to a high tunnel, we observed a severe salinity problem on tomatoes. Approximately one month after planting , most tomato plants in the affected area had not sent out any new leaves. Roots did not grow at all (Figure 1). After conducting a soil test, very high soluble salt level explains these symptoms. This article reviews the basics of soil salinity. Salinity describes salt content in the soil. Virtually all fertilizer materials are salts, but they vary in their effects to increase salt concentration in soil solutions. In a field situation, precipitation in the form of rain and snow tend to leach salts. Since high tunnels exclude rain and snow, elevated salt levels are a common concern for high tunnel vegetable growers. Table 1 are the salt indexes of common fertilizers. If you are using a premixed fertilizer such as 12-12-12, check the fertilizer components on[Read More…]
Census data showed that in 2014 Indiana (12 acres), Illinois (11 acres) and Kentucky (13 acres) dedicated a very small portion of their food crop acreage to production under protection. According to the USDA National Agriculture Statistical Service 2014 Horticulture Specialties Census, of all the states surrounding Indiana, Ohio and Michigan have grown and sold the most food crops under protection, 24 and 25 acres, respectively. The use of high tunnels for vegetable production seems to be a novelty in the Midwest. But it can be a very important tool for every vegetable grower as it can be used to modify the growing environment for crop earliness, to protect the growing crop against environmental stress, to reduce disease and insect pressure and to extend the growing season. Covering the soil with a high tunnel prevents natural rainfall from washing or leaching nutrients and soluble salts from the soil, can lead[Read More…]
Soil pH plays an important role in plant nutrition. However, we might not be familiar with how nitrogen fertilizers influence soil pH over time. This article explains how nitrogen fertilizers influence soil pH over time and discusses some considerations in choosing N fertilizers. Plants can take up N in two forms: ammonium and nitrate. Ammonium (NH4+) is positively charged, while nitrate (NO3–) is negatively charged. When plant roots take up a charged ion, they typically release an ion with identical charges to maintain a balanced pH in plant cells. Following this rule, plants release a hydrogen ion (H+) when taking up an ammonium ion; and release a hydroxide ion (OH–) when taking up a nitrate ion. As a result, the net effect of taking up nitrate-N is to increase soil pH around root zones; taking up ammonium-N reduces rhizosphere soil pH. Nitrogen fertilizers contain N in the forms of ammonium,[Read More…]
There are certain questions within our culture for which there are simply no good answers. For example, how many times have we heard the classic question, “If a tree falls in a woods and there’s no one to hear it, does it still make a sound?” One question I’ve been asked recently, for which the answer is equally elusive, is “How long must I wait to grow vegetables after applying manure to the field?” With the 2015 season quickly winding down, it will soon be time to start making plans for next year’s crops. Part of those plans will undoubtedly include the question of manure use. While manure is a good source of plant nutrients and organic matter, it may also contain human pathogens that can be transferred onto fresh fruits and vegetables. After manure is applied to a field, the bacterial community in the manure changes as it adapts[Read More…]
Crop production, decomposition of organic matter, using ammonium-producing nitrogen fertilizers, and rainfall all lower soil pH. To maintain soil pH in the optimal range (6.5 to 6.8) for vegetable production, periodic application of lime is needed. The primary form of agricultural lime is calcium carbonate (CaCO3). It is the carbonate (CO3^2-) part that brings up soil pH. Whenever lime is applied, a large amount of calcium is also added to the soil. The good news is that calcium is an essential plant nutrient. Several vegetable problems that we are familiar with are caused by calcium deficiency for example, blossom end rot of tomatoes and peppers, and tip burn of cabbages. However, it should be noted that excess calcium might interfere with plant available magnesium and potassium. Therefore, it is always better to keep a balance of those nutrients. Some lime products are specified as dolomitic lime. Dolomitic lime is common[Read More…]
You might remember seeing cation exchange capacity in soil test reports. Recently, I have been asked about what it means. This is one of the important soil characteristics that we need to understand. Firstly, we need to know what cations are. Cations are positively charged ions. There are several. The ones very important for plant growth are calcium (Ca2+), magnesium (Mg2+) and potassium (K+). Soil particles are negatively charged. They can hold positive charged cations. When plants absorb nutrients from the soil solution, these bound nutrient cations are exchangeable with other cations in the soil solution and become plant available. Therefore, CEC describes the soil’s capacity to supply nutrient cations to the soil solution for plant uptake. Sands do not have the quantity of negative charges that clays and organic matter do. Thus sandy soils generally have the lowest CEC. Soils with lower CEC have less ability to retain cation[Read More…]
