Unfertilized Grass Research Articles

Effects of ‘Coastal’ Bermudagrass Fertilization Levels and Age of Regrowth on Fall Armyworm (Lepidoptera: Noctuidae): Larval Biology and Adult Fecundity1

Fall armyworm, Spodoptera frugiperda (J. E. Smith), larval survival, weight at 10 days, developmental rate, and pupal weight were significantly greater on fertilized than on unfertilized ‘Coastal’ bermudagrass, Cynodon dactylon (L.) Pers. A combined analysis over three tests also showed that fecundity was significantly greater for moths that originated from larvae that fed on fertilized grass than for moths that originated from larvae that fed on unfertilized grass. Fall armyworm responses to bermudagrass regrowth were more varied, but in two of the three tests larval survival, weight at 10 days, and developmental rate were significantly greater on young regrowth than on older regrowth. Pupal weight and fecundity showed no consistent relationship with stage of bermudagrass regrowth. Increased ‘Coastal’ bermudagrass fertilization and younger regrowth primarily influenced larval development, with little influence on pupal development. Calculations showed that fall armyworm population could increase 45- to 225-fold in highly fertilized bermudagrass pastures compared with unfertilized bermudagrass.

SEED YIELD OF ALTAI WILD RYEGRASS AS INFLUENCED BY ROW SPACING AND FERTILIZER

A study was conducted from 1969 to 1977 to determine the effect of row spacings and applications of N and P fertilizer on the productivity of Altai wild ryegrass (Elymus angustus Trin.). The optimum row spacing for highest seed production was 120 cm and the optimum fertilizer treatment was 25 kg N/ha plus 25 kg P/ha annually. Doubling the rate of N or N plus P did not significantly increase the seed yield over that obtained from grass receiving the 25 kg N plus 25 kg P per hectare rate. Fertilizer treatments containing P tended to result in a more stable year-to-year response than those containing only N. Altai wild ryegrass grown in 30-cm row spacings produced higher dry matter yields for the first 4 yr than that grown in wider-spaced rows. However, in the last 4 yr highest yields were obtained from grass seeded in rows spaced 150 cm apart. Grass receiving an annual application of 50 kg N/ha plus 50 kg P/ha produced significantly more forage than that given, only 25 kg N/ha, both of which outyielded unfertilized grass.

The performance of beef animals on a permanent pasture*

AbstractBetween 1967 and 1975, 416 beef animals were grazed rotationally on an indigenous pasture (11.65 ha) containing Festuca rubra, Holcus lanatus, Poa trivialis and Agrostis spp. and dicotyledonous plants, but little Lolium perenne or Trifolium repens. Part of the land received fertilizer nitrogen at rates varying between 120 and 200 kg h−1 each year and part did not; some of the land was grazed only and some was cut and then grazed.The winter gains of the animals (approx. 45 kg) were more variable and less than the summer gains (approx. 155 kg). Summer gain was inversely correlated with winter gain. An increase in initial weight of animals purchased from 1973 onwards did not increase either winter or summer gain. Friesians gained more than Hereford‐cross animals during the winter, but there was no difference in summer gain.During 9 years the average animal weight per grazed ha in April was increased from 1260 to 2122 kg. The mean total gain on 1165 ha of grass was 6486 kg per annum in the first 3 years and 7266 kg per annum in the last 3 years. The average annual production was 590 kg live‐weight gain and 1.01 t hay or 2.33 t silage per ha. The output of fertilized grass in 1975 was calculated as 842 Livestock Unit Grazing Days (LUGD) per ha and that from unfertilized grass as 360 LUGD per ha. The overall output of utilized metabolizable energy in 1975 was 59–7 GJ h−1, with 69.3 GJ h−1 from fertilized grass and 29.8 GJ h−1 from unfertilized grass.

Cutting and Fertilizing Grassland for Winter Goose Management

An experiment to investigate the effect of nitrogenous fertilizer and autumn cutting on the winter use of salting pasture by wild white-fronted geese (Anser albifrons) is described. Geese showed a high degree of preference throughout winter for fertilized vegetation, which had a higher nitrogen (protein) content than unfertilized grass. Cut areas were also preferred early in the season. This was related to the ease of movement and better visibility afforded, as well as a possible effect on feeding efficiency. Overall use of fertilized areas was 42 percent higher than controls, of cut areas 32 percent, and of those both fertilized and cut 87 percent. The treatments were applied to two vegetation zones, which were also used differentially by feeding geese. Applications to the management of goose refuges are discussed. J. WILDL. MANAGE. 39(1):163-167 In a study of the grazing of white-fronted geese on a salting pasture (grassland which is covered by tidal brackish water a few times annually) (Owen 1971), it was shown that the birds had preferences among the five distinguishable vegetation zones. Preferred zones were used first, and less vegetation was left on preferred areas. The preferred vegetation was of higher nutritional value, and the nutritional value of single grass species decreased as vegetation height increased (Owen 1973). This paper describes an experiment on part of this salting, known as the Dumbles, at Slimbridge, Gloucestershire, in the winter 1972-73 to investigate the effects of fertilizing and cutting the vegetation on its use by wild white-fronted geese. The area is visited by large numbers of people, and one of the aims was to determine whether geese could be enticed to make greater use of sites close to observational facilities provided by the Wildfowl Trust. The work was carried out while I held a post at the Wildfowl Trust financed by the Natural Environment Research Council. I am indebted to A. J. Stewart for help with field and laboratory work, and to S. E. Allen for the nutritional analyses. R. C. Lippiat and T. C. Meredith carried out the cutting and fertilizing operations. G. V. T. Matthews made useful criticisms

Implicit Estimate of Residual Nitrogen Under Fertilized Range Conditions in the Northern Great Plains1

AbstractInformation concerning carryover of fertilizer nitrogen in the plant‐soil system is necessary to determine optimum fertilizer policies for dryland grasses in semiarid regions. A primary contribution of this paper is the presentation and illustration of a dynamic model for estimation of carryover nitrogen. The carryover relationship is estimated implicitly through yield response as opposed to direct measurements on nitrogen. Data from an experiment designed to evaluate the effects of nitrogen and phosphorus fertilizers and seasonal precipitation on the yield and composition of bromegrass (Bromus inermis)‐crested wheatgrass (Agropyron cristatum) hay were analyzed with the model. A polynomial yield response equation in the two variables, plant‐available nitrogen and seasonal precipitation, was estimated simultaneously with a first order difference equation assumed to describe the residual nitrogen relationship.Statistical estimation was by nonlinear regression techniques. The proportion of nitrogen available in year t which was carried over to year t+1 was estimated at approximately 54%, taking precipitation at the mean of a 32‐year series, and the standard error associated with percent carryover was 3.4. A maximum yield of 2072 kg/ha (1849 lb/acre) resulting from 268.99 kg/ha (240 lb/acre) of available nitrogen is predicted under average precipitation conditions. The fact that an economic determination of the optimal level of nitrogen to maintain in the soil must include a consideration of carryover and the relevant interest rate is demonstrated. In equilibrium the optimal level of nitrogen is 89 kg/ha (79 lb/ acre), assuming an interest rate of 10%, a forage value of $.0165/kg ($15/ton), and a nitrogen fertilizer cost of $.22/kg ($.10/lb) with the costs of spreading fertilizer ignored. The maintenance of this level of nitrogen in the soil would increase average net returns over unfertilized grass by $2.27/ha or by about 20%.

Mineralization of Nitrogen in Grass Roots

AbstractThe mineralization of fertilizer N immobilized in grass roots (Bromus inermus L.) is of major importance in regulating the use of N fertilizers on grassland. Grass roots varying in N content were therefore incubated with soil for 10 weeks at 30C, and the net rate of mineralization was measured. Rate of N mineralization during incubation was controlled to a large extent by the N content of the root material—mineralization of N contained in grass roots followed much the same pattern as for that in any other plant tissue. Incubation of unfertilized grass roots (0.84% N) resulted in net immobilization of mineral N. Incubation of N‐fertilized grass roots (containing 1.44% N) resulted in a net increase in mineral N. For both root materials the changes in mineral N were in proportion to the amount of root material added.

The voluntary intake and digestibility, in sheep, of chopped and pelleted Digitaria decumbens (pangola grass) following a late application of fertilizer nitrogen.

1. Experiments were conducted with wether sheep in 1964 and 1965 fed pelleted or chopped mature Digitaria decubemes Stent (pangola grass) bay containing different crude protein contents. The voluntary intake of food, digestibility of dry matter and nitrogen, nitrogen retention and apparent time of retention of feed organic matter in the reticulo-rumen were measured. The different crude protein contents of the grass were obtained by applications of urea to the sward 14 and 28 days before cutting for hay in 1964 and 1965 respectively. This treatment increased the crude protein content of the dry matter from 4.9% to 8.7% in 1964 and from 3.7% to 7.2% in 1965. The size of the particles of the ground hay before pelleting is given.2. The mean voluntary intake of chopped fertilized grass was 10% and 54% greater than that of the unfertilized; the voluntary intake of pellets made from fertilized grass was 35% and 75% greater than of those made from the unfertilized grass in 1964 and 1965 respectively.3. The voluntary intake of pellets of unfertilized grass was 7% and 14% greater than that 30% greater than that of chopped fertilized grass in 1964 and 1965 respectively.4. The digestibility of the pellets was less than that of the chopped grass.5. The apparent digestibility of the feed nitrogen was increased by the fertilizer nitrogen, but grinding and pelleting had no consistent effect. Sheep eating chopped or pelleted fertilized hay were in positive nitrogen balance.6. The apparent retention time of organic matter in the reticulo-rumen was longer when the sheep were eating chopped hay than when they were eating pellets. In 1964 the apparent retention time of organic matter in the reticulo-rumen was shorter for chopped and pelleted unfertilized grass than for chopped and pelleted fertilized grass, but in 1965 the order was reversed.7. The relationship between voluntary intake, apparent retention time of organic matter in the rumen and the protein content of the food is discussed.

Variations in Initial Composition of Orchardgrass as Related to Silage Composition and Feeding Value

Summary Eight lots of orchardgrass, representing a wide range in composition, were produced on areas either heavily fertilized or unfertilized with nitrogen. Fertilized grasses were higher in crude protein content, but lower in dry matter, nitrogen free extract (NFE) sugar, and ratio of sugar to protein than the unfertilized counterparts. Silages from fertilized grasses were higher in pH, butyric acid, and ammonia, and in some cases lower in feeding value than the companion silages from unfertilized grasses. Multiple regressions of silage quality criteria on original forage composition measurements and of dry matter consumption by dairy cattle on silage quality criteria were calculated. The peculiar characteristics and ensiling requirements of high-nitrogen grasses were discussed.

Effect of Soil Temperature and Nitrogen Fertilization on the Growth of Soft Chess (Bromus mollis) at Two Elevations

SynopsisApplied nitrogen increased the growth rate of the grass very little when the average soil temperature was below 45° F. Grass fertilized with nitrogen showed the greatest increase in growth compared with unfertilized grass when the average soil temperature was between 47° and 55°. When the temperature went above 55° the difference between unfertilized and fertilized grass decreased.

STUDIES WITH FERTILIZED PASTURES ON A HEAVY TEXTURED SOIL IN NORTHERN ALBERTA

Yields of herbage, animal gains, carrying capacity and TDN production were determined for three pasture swards grown on a Grey Wooded soil (Albright-Hythe series) in the Peace River region of northern Alberta over the period 1953 to 1956 inclusive. Sheep were used as grazing units. Fertilizer treatments of nil, ammonium phosphate (11-48-0) at 300 pounds per acre and ammonium nitrate (33-0-0) at 100 pounds per acre were applied annually to pastures of creeping red fescue, creeping red fescue-alfalfa and bromegrass-alfalfa.Productivity obtained with unfertilized grass-legume mixtures was almost double that for unfertilized grass grown alone. Increased production attributable to alfalfa was also obtained, although to a lesser degree, where fertilizers were used. Pastures of creeping red fescue seeded alone and with alfalfa responded markedly to applications of nitrogen while responses to phosphorus were negligible. Conversely, bromegrass-alfalfa pastures responded strongly to applications of phosphorus and only slightly to nitrogen.