How a corn plant develops

There’s more than meets the eye in a field of growing corn. One way to look behind the scene is to consider the cornfield as a complex and constantly changing community. It is a manufacturing community, with many thousands of factories per acre. Every corn plant is a factory that produces dry matter. The corn plant is one of the most efficient factories in the world!https://lib.dr.iastate.edu/specialreports/1045/thumbnail.jp

Available-sulfur status of some representative Iowa soils

Greenhouse experiments with ryegrass were conducted to evaluate and characterize plant availability of native and added sulfur in samples of Iowa soils. Fourteen surface soil (0-6 inches) and five subsoil (18-24 inches) samples from different sites in Iowa and two surface soil samples from S-deficient out-of-state sites were studied. Laboratory analyses were made to characterize the soil samples and to evaluate the results of different extractants as indexes of the S-supplying abilities of the soils. Plant uptake of S from the soil samples with no added S during a 202-day cropping period (five harvests) varied from 1 to 39 mg S/1500 g of soil (39 mg S/1500 g of soil is approximately equivalent to 50 lb S/acre six inches of soil in the field). Sulfur uptake was greatest during the first 70 days of cropping (two harvests), but continued at a slower, essentially constant daily rate throughout the rest of the cropping period. Although relatively slow for all soil samples, the rate of S uptake during this later cropping varied markedly among the different soil samples, with the rates for the surface soil samples being directly related to the amounts of S taken up by the plants in the earlier cropping period. The rates of uptake were very slow from most of the subsoil samples, and many plants on these subsoils died. Air-drying the soil samples before cropping resulted in increased plant yields and increased S uptake by the plants

Comparisons of laboratory and greenhouse indexes of nutrient availability in soils

Accurate indexes of the availability to plants of nutrients in soils are needed for comparisons of different chemical tests to determine which tests should be used in the laboratory for any given group of soils. This study was conducted to develop and improve techniques for obtaining such standard indexes of nutrient availability to plants. Emphasis was placed on: (a) treating the soil similarly (or uniformly) before testing in the greenhouse and laboratory and (b) avoiding treatments during the greenhouse cropping that might influence the availability of the soil nutrient being tested. The greenhouse technique involved growing plants on undried samples of 24 different soils. Water was added directly to the soils during plant growth, but nutrients other than the one being tested were added by a method which minimized contact with the soil

Plant availability of added phosphorus in different Iowa soils

Laboratory and greenhouse experiments were conducted to study the availability of fertilizer P in 20 samples of different soils representing 10 of the principal soil associations in Iowa. Ryegrass plants recovered an average of approximately 50 percent of the added fertilizer P during a 385-day cropping period in the greenhouse. It appeared that continued cropping would have resulted in very little additional recovery of the added P. Differences in recovery of the added P from the different soils were relatively small, despite differences in rate of fertilizer addition or differences in soil pH, CaCO3 content, level of available soil P, soil organic matter content, and soil texture

How a soybean plant develops

Compiled in this publication are years of research, study and observation o f exactly how a soybean plant develops. Photographs and accompanying text record the findings for each major stage of development in the soybean plant’s life.https://lib.dr.iastate.edu/specialreports/1050/thumbnail.jp

P and K Fertilizers for Corn - How to Apply

More Iowa corn acres could be fertilized profitably with phosphorus and potassium. Both hill (row) and broadcast application have their place. Here\u27s what research tells us about methods of application

The Relationship of Nitrification Rate of the Soil and Nitrogen Content of the Corn Leaf to the Yield of Corn

In this study the capacity of the soil to supply available nitrogen to corn was measured by nitrification rate of the soil and by the nitrogen content of corn leaves.Rotation plots on the Agronomy Farm, Lincoln (NE), offered an opportunity to study the relationship of both the nitrification rate of the soil and of the nitrogen content of the corn leaf to yields of corn on a typical non-irrigated soil.A moisture-fertility-spacing experiment of the North Platte Experiment Substation provided a source of samples for studying the relationship of nitrogen content of corn leaves to yield of corn on an irrigated soil. In the rotation plots a highly significant correlation was obtained between nitrification rate of the soil and yield of corn.In these plots the highest yields have been obtained from the rotation that included two years of sweet clover and an application of manure. Yields of corn and nitrification rates were highest immediately following a legume in the rotation or an application of manure and decreased as the length of time between the crop of corn and the legume or an application of manure increased.The very low yield of corn immediately following alfalfa was one outstanding exception to this.This was probably due to a moisture deficiency induced by the alfalfa. In the rotation plots the nitrification rate was correlated with the total nitrogen content of the soil.Total nitrogen content of the soil was about 0.008 per cent greater in plots having rotations that contained two years of a legume or an application of manure than it was in those plots where rotations contained no legume or manure.Total nitrogen content of the soil in plots where rotations contained two years of legume and application of manure exceeded by about 0.018 per cent that in plots where rotations contained no legume or manure. In the moisture-fertility-spacing experiment, the nitrogen content of the corn leaves was influenced by fertility levels and plant population and was highly significantly correlated with yield (r = 0.84). Advisor: H. F. Rhoade