2-inch Depth Research Articles

Trapping cabbage maggots with plant bait and allyl isothiocyanate.

Allyl isothiocyanate was as effective as fresh cruciferous plants in trapping adult Hylemya brassicae (Bouche) for population studies. The synthetic bait caught as many males as females, suggesting that oviposition attraction is not the sole function of mustard oils to cabbage maggots. Four emergence peaks of flies were observed over the season of 1970 in Geneva, New York. Soil thermal units of 230 for first emergence and a mean of 1110 between peaks, as measured at a 2-inch depth under a growing row of vegetation, correlated closely with those accumulations previously established under controlled conditions.

Seasonal Changes in Soil and Air Temperature at Three Locations in Puerto Rico, 1963-67

Soil temperature data at Río Piedras in the north, Lajas in the southwest, and Fortuna in the south, are given in this paper for the 5-year period 1963- 67. Seasonal variations in soil and air temperatures follow distinct patterns somewhat, depending on the nature of the soil cover and rainfall. Mean maximum and minimum temperatures at the 2-inch depth, respectively, are: Río Piedras, 96.2° F. and 79.6° F.; Lajas, 102.1° F. and 69.0° F.; and Fortuna, 93.2° F. and 79.1° F. The corresponding soil temperatures at the 8-inch depth, respectively, are: Río Piedras, 80.5° F. and 77.4° F.; Lajas, 83.4° F. and 77.8° F.; and Fortuna, 85.7° F. and 82.7° F. The differences and trends of soil temperature at 2-inch and 8-inch depths can find adequate explanation when soil moisture and soil cover are considered. However, the differences between maximum and minimum soil temperatures at 8 inches of depth are roughly one fifth of the corresponding ones at the 2-inch depth. The maximum and minimum air temperature at Lajas, Fortuna and Río Piedras are much more similar to each other than the corresponding soil temperature, especially at the 2-inch depth. This is mainly because air temperature is rather measured on a macro and integrating scale while soil temperature measurements exhibit localized effects of soil cover and soil moisture. It was found that highly significant 2-inch soil-air temperature relationships are evident under bare soil conditions. The same relationships were not significant under sod cover at Fortuna.

Metabolism of Siduron by Barley and Crabgrass

At rates as high as 40 lb/A, 1-(2-methylcyclohexyl)-3-phenylurea (siduron) did not reduce the growth of crabgrass (Digitaria spp.) seedlings although it was highly toxic to germinating seeds. Siduron placed at the 2-inch soil depth reduced root growth but not shoot growth of crabgrass. Barley (Hordeum vulgare L., var. Trail) roots, like crabgrass, were more affected than shoots. Carbonyl labeled siduron-14C was absorbed by both barley roots and shoots. Siduron-14C was translocated from roots to shoots but not from shoots to roots. Analysis of the extracts from plants treated at various times revealed that no metabolites of siduron-14C were present. Siduron must be present at the time of seed germination to effectively reduce plant growth.

Soil Aeration as Affected by Organic Matter Application

AbstractThe effect of the method of incorporation of organic matter under various conditions of soil moisture and soil compaction on the composition of soil air was the object of this research. Application of fresh chopped alfalfa resulted in a pronounced depression of the oxygen content of the soil air. The order of decreasing oxygen content for the different methods of application was: check > surface mixed > layer at 2‐inch depth > surface application. High moisture content and compaction of the soil increased the time during which the oxygen content remained below 15% at 8‐inch depth. Both the oxygen and the carbon dioxide contents were determined at the 1‐, 3‐, and 8‐inch levels, as well as the amount of carbon dioxide given off at the soil surface.

The Use of Regression in Range Research

of thesis submitted in partial fulflUment of the requirements for the degree of Master of Sciencee, Department of Range & Forestry, Agricultural & Mechanical College of Texas, 1955. Five important range grasses of Texas were planted during the fall and winter of 1953-54, on an abandoned cultivated field near College Station, Texas. Plantings of big bluestem, silver bluestem, Indian grass, side-oats grama, and little bluestem were made on four dates: November 21, January 2, February 6 and March 5. Plantings were made of each species on the surface and at depths of 1/4, '/2, 3/4, 1 and 1'/2 inches. On May 27, three fertilizer treatments were made: top dressing, hand dressing applied at the rate of 90-45-0 per acre and no fertilizer. All plots were weeded at various intervals. Plantings of big bluestem resulted in relatively poor stands with few plants. A majority of these, plants resulted from the February and March plantings. Establishment 'of plants was greatest for the 1/4and /2-inch depth plantings. Relatively large numbers of silver bluestem plants were established at all planting dates, with maximum in March and minimum in February. Planting at depths of 1/4 and 1/2 inch resulted in greater establishment than at other depths. Planting at 11/2-inch depth resulted in failure for all dates of planting. Indian grass produced a comparatively substantial number of plants for all dates of planting. This grass showed the least variation in plant numbers for the various dates of planting of all the grasses observed. Plantings at depths of 1/4, 1/2 and 3/4 inch resulted in from fair to excellent stands for all dates of planting. All 11/2-inch depth plantings rated poor. Results from surface plantings were erratie, and ranged from no plants to good stands. Side-oats grama produced the greatest number of plants of any of the grasses. The November and January plantings resulted in poor emergence whereas the February and March plantings resulted in good to excellent emergence. Planting depths from ,4 to I inch for the February and March plantings resulted in stands that rated excellent. Surface plantings rated fair to excellent. Planting depths of 11/2 inch resulted in poor stands for all dates of planting. Counts of lit-tle bluestem were considerably higher for the February and March plantings than for the November and January plantings. Planting depths of 1/4 and 1/2 inch for this grass resulted in the best stands of any of the depths. Surface and 3/4-inch depths resulted in poor to fair stands, 1-inch depths in poor to no stands, and 11/2-inch depths in no stands. Fertilizer applied as a top dressing to the five grasses appeared to give better results, as related to height of plant and herbage production per foot of vegetation, than the hand dressing and no fertilizer. Big bluestem was the only grass not reflecting these results. Indications were that band dressing was slightly les favorable than no fertilizer. This may have been due to poor soil moisture conditions at the time of application and for a considerable period thereafter.-JAMES E. ANDERSON, Department of Animal Husbandry, New Mexico Agricultural & Mechanical College, State College,, New Mexico. This content downloaded from 207.46.13.150 on Thu, 28 Jul 2016 04:32:38 UTC All use subject to http://about.jstor.org/terms