Differential effect of carbon sources on nitrogen transformation in Hawaiian soils
SummaryMineralization of native N was curtailed by addition of carbon sources in all soils tested. A readily available energy source, sucrose, accelerated and increased the immobilization of native as well as added N more than a slowly available energy source, sugar cane bagasse. Addition of N as ammonium sulfate increased CO2 production in only one out of five soils when no energy source was added. With energy source addition, N addition enhanced CO2 production in most soils. Without any treatment, the immobilization of added N was related to the C:N ratio of the soil; maximum immobilization occurred in the soil with the widest C:N ratio.
RATES OF IMMOBILIZATION AND RELEASE OP NITROGEN FOLLOWING ADDITIONS OF CARBONACEOUS MATERIALS AND NITROGEN TO SOILS
Numerous experiments have been reported (1, 4–8) that show the quantity of nitrogen required by soil microorganisms in the decomposition of carbonaceous materials, such as straw. These values usually vary between 1.1 and 2.0 per cent of the dry weight of readily decomposable plant materials, including the nitrogen originally present in the plant material, and are often much lower for very woody materials (2). In such experiments, immobilization and mineralization proceed simultaneously; that is, nitrogen that is first immobilized may be in part released later. Nitrogen requirement values, as ordinarily obtained, are, therefore, net values for the given experimental period chosen by the investigator. Few data have been published that show quantitatively how nitrogen tie-up and release vary at short intervals of time and also with rate of CO2 formation. This paper presents data of this type.
Pig Vocalizations Under Selected Husbandry Practices
Acoustical characteristics of vocalizations of sows, piglets, and nursery pigs under selected husbandry practices were analyzed with a digital signal processing system. The duration (D) and major energy-resonance frequency (P) for each call were determined as follows: a) processing of piglets (D = 0.81 s and f* = 3 700 Hz); b) food anticipation of breeding-gest ation sows (2.50 s and 3 000 Hz); c) isolation of piglet (0.34 s and 500, 3 500 Hz); d) startling of nursery pigs (0.29 s and 900 Hz); e) sows in heat (3.07 s and 1 375 Hz); f) farrowing (0.10 s and 3 000 Hz); g) sow nursing (0.15 s and 1 000 Hz); and h) mate greeting of sow (0.13 s and 1 000 Hz). Calls a) to d) are responses to human generated stressors, and calls e) through h) responses to social and physiological states of the pigs. Thus, vocalizations can be segmented for different pig production situations.