Soil Fertility and Fertilizers

Tags

A Case Study: What Cover Crops Could Achieve in High Tunnels in the Middle of Summer?

August 4, 2016 - From Issue: 618

Figure 2. Cowpea was worked into the soil

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…]

Crops

Tags

Greenhouses & High Tunnels / Soil Fertility and Fertilizers

How Much Nitrogen is Too Much for Pumpkins

June 8, 2016 - From Issue: 614

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…]

Crops

Pumpkins

Tags

Salt Accumulation for Vegetable Production in High Tunnels

May 10, 2016 - From Issue: 612

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…]

Crops

Tomato / Vegetable Crops - General

Tags

Greenhouses & High Tunnels / Soil Fertility and Fertilizers

Importance of Water and Soil Analysis for High Tunnel Growers

April 12, 2016 - From Issue: 610

By: Petrus Langenhoven

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…]

Crops

Protected Culture and Season Extension / Soil Fertility and Fertilizers

Tags

Effects of Nitrogen Fertilizers on Soil pH

April 11, 2016 - From Issue: 610

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…]

Crops

Tags

Managing Manure – How Long is Long Enough?

October 29, 2015 - From Issue: 607

By: Scott Monroe

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…]

Tags

Food Safety / Soil Fertility and Fertilizers

Liming

September 17, 2015 - From Issue: 606

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…]

Crops

Tags

Crop Culture / Soil Fertility and Fertilizers

Cation Exchange Capacity (CEC): What Does It Mean?

September 4, 2015 - From Issue: 605

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…]

Crops

Tags

Mid-Season Nitrogen Management in Pumpkins

August 4, 2015 - From Issue: 603

By: Dan Egel

Pumpkins are off to good start and vines are starting to run, which means it is time to think about making a sidedress application of nitrogen. Typically, I recommend to split nitrogen applications half preplant and half sidedress. This is especially beneficial given all of our rain this season. If you relied on preplant N alone, with all of the rain, you may very well have lost almost all of your nitrogen with plants just now starting to set fruit. In my personal scenario, on light colored forest soils (common in So. IL and IN, 1.5-2.5 % organic matter) and given no-till with cereal grain residue I generally shoot for around 100-110 lbs. actual N per year (this would be decreased with more fertile, high organic matter soils) with about 50 lbs. of that at sidedress. In a tilled field, you could decrease this recommendation to around 80 lbs. actual N/A per year. This difference can[Read More…]

Crops

Cucurbits / Pumpkins

Tags