Sowing

About: Sowing is a research topic. Over the lifetime, 33888 publications have been published within this topic receiving 273438 citations. The topic is also known as: seeding.

The effects of elevated CO2 on seed production and seedling recruitment in a sheep-grazed pasture.

Abstract: Seed production and seedling recruitment were measured over 2 years under ambient (360 ppm) and elevated (475 ppm) atmospheric CO2 in a free air carbon dioxide enrichment (FACE) experiment, carried out in a sheep-grazed pasture on dry, sandy soil in New Zealand. In both years elevated CO2 led to more dispersed seeds of the grasses Anthoxanthum odoratum, Lolium perenne and Poa pratensis, the legumes Trifolium repens and T. subterraneum and the herbs Hypochaeris radicata and Leontodon saxatilis. The increased seed dispersal in A. odoratum, H. radicata, Leontodon saxatilis and T. repens reflected both more inflorescences per unit area and more seeds per inflorescence under elevated CO2. The increased seed dispersal in Lolium perenne, P. pratensis and T. subterraneum was due solely to more inflorescences per unit area. The number of seedlings that emerged and survived to at least 7 months of age was increased by elevated CO2 for H. radicata, Leontodon saxatilis, T. repens and T. subterraneum in both years and for A. odoratum and Lolium perenne in the first year. For species where increased seedling recruitment was noted, there was a significant positive correlation between seed production in summer and seedling emergence in the following autumn and winter, and sowing 200 extra seeds per species m–2 resulted in more seedlings compared to unsown controls. Elevated CO2 did not affect seedling survival in any species. There was no measurable effect of elevated CO2 on canopy and soil surface conditions or soil moisture at the time of seedling emergence. The results suggest the dominant effect of elevated CO2 on seedling recruitment in this pasture was an indirect one, reflecting effects on the number of seeds produced. The biomass of H. radicata, Leontodon saxatilis, T. repens and T. subterraneum in the above-ground vegetation was greater under elevated than ambient CO2. However, the size of individual seedlings and mature plants of these four species was unaffected by elevated CO2. The results indicate an important way elevated CO2 influenced plant species composition in this pasture was through changes in the pattern of seedling recruitment.

Soybean Growth and Development in Various Management Systems and Planting Dates

Abstract: Soybean [Glycine max (L.) Merr.] has the ability to produce similar yields across a broad range of management systems and planting dates. Our objective was to better understand growth factors affecting yield component compensation in the upper Midwest under different management systems. An older cultivar, Hardin, and two newer cultivars, DeKalb CX232 and Spansoy 250, were grown in five management systems during four growing seasons from 1997 to 2000. Four of the five management systems were located near Arlington, WI, on a silt loam soil consisting of conventional and no-tillage systems with and without irrigation. The fifth management system was located near Hancock, WI, on a conventionally tilled, irrigated sandy loam soil. Yield component compensations gave similar grain yield among cultivars, planting dates, and management systems. At R6, CX232 and Spansoy 250 averaged greater dry matter (DM) accumulation, leaf area index (LAI), and crop growth rate (CGR) than Hardin. Early planted soybean had more total DM than the late-planted soybean. No-tillage systems produced more total DM, LAI, and CGR after R3 than the two conventional tillage systems at Arlington. Irrigated systems had higher LAI than the nonirrigated systems. These results indicate that the compensatory growth and alterations in plant development among cultivars, management systems, and planting dates had no impact on soybean yield.

Tillage and crop residue management significantly affects N-trace gas emissions during the non-rice season of a subtropical rice-wheat rotation

Abstract: Field operations of tillage and residue incorporation could have potentially important influences on N-trace gas fluxes, though poorly quantified. Here we studied the effects of straw incorporation in the preceding rice season and no-tillage prior to wheat sowing on nitric oxide (NO) and nitrous oxide (N2O) emissions during the non-rice period of a typical rice-wheat rotation in the Yangtze River Delta. Compared to conventional management practice (no straw incorporation along with rotary harrowing tillage to 10 cm before wheat sowing), straw incorporation alone decreased cumulative N2O emissions over the entire non-rice period by 32% (1.53 vs. 2.24 kg N ha-1, P

Effects of Injected Liquid Cattle Manure on Growth and Yield of Winter Wheat and Soil Characteristics

Abstract: Liquid cattle (Bos taurus) manure should be applied to soils in such a manner that would improve soil fertility and crop production without causing salinity problems or increasing NO - 3 levels. This study investigated the influence of liquid cattle manure on winter wheat (Triticum aestivum L. cv. Yecora) germination, growth, and nutrient utilization. Four treatments were applied in the same plots in a 4-yr field experiment with winter wheat: (i) application of 40 Mg ha -1 yr -1 liquid dairy cattle manure (wet weight basis) before sowing; (ii) single application of 120 and 26 kg ha -1 yr -1 N and P, respectively, as inorganic fertilizers before sowing; (iii) as in ii, but with split application of N, half the amount before sowing and the rest at tillering; and (iv) no fertilization. The biological evaluators used to compare the effect of the treatments were (i) number of seedlings per square meter at tillering for the first year only and (ii) dry biomass at heading and harvest; plant concentration and uptake of N, P, and K; and grain yield for every year of experimentation. The results showed that application of manure did not affect seed germination but resulted in a significant increase in dry biomass at the two growth stages and in grain yield and nutrient uptake, similar to the inorganic N and P fertilization. The amounts of soil available NO 3 -N and P were significantly increased while at the end of the field experiment, soil salinity, organic C, and total N levels remained unchanged.

Changes in weed community composition as influenced by cover crop and management system in continuous corn

Abstract: Weed suppression by cover crops grown during the winter fallow period in continuous corn may lead to a reduction in herbicide use. Rye, crimson clover, and subterranean clover cover crops were compared with corn stubble under a conventional management system (CS) that included plowing and use of preemergence residual herbicides and a low-input management system (LIS) that included no-tillage and use of a presowing nonresidual herbicide for three consecutive years (1994–1996). Cover crop and above-ground weed biomass prior to desiccation were not influenced by management system. Cover crop biomass ranged from 1,420 to 5,657 kg ha−1 for rye, from 563 to 4,217 kg ha−1 for crimson clover, and from 563 to 4,248 kg ha−1 for subterranean clover. At crop planting, rye reduced weed biomass from 54 to 99%, crimson clover from 22 to 46% (with a negative value in 1995), and subterranean clover from 21 to 67%. Weed growth suppression was usually higher in years when cover crop biomass was higher. There were n...