scholarly journals Agroecological problems of intensive agriculture on drained lands

2021 ◽  
Vol 17 (4) ◽  
Author(s):  
N.V. Tsuman ◽  
V.O. Zinchenko
Keyword(s):  
Intensive Agriculture

Organochlorine Residues in Brook Trout and Yellow Perch From New Brunswick and Nova Scotia (Canada) Lakes

1987 ◽  
Vol 22 (3) ◽  
pp. 352-364
Author(s):  
R. Peterson ◽  
S. Ray
Keyword(s):  
Nova Scotia ◽  
New Brunswick ◽  
Brook Trout ◽  
Yellow Perch ◽  
Intensive Agriculture ◽  
Fish Tissues ◽  
North Central ◽  
Ddt Metabolites ◽  
Headwater Lakes

Abstract Brook trout and yellow perch collected while surveying New Brunswick and Nova Scotia headwater lakes were analyzed for DDT metabolites, chlordane, hexacyclohexane isomers, hexachlorobenzene, toxaphene and PCB’s. Concentrations of DDT metabolites were much higher from fish taken from lakes in north-central N.B. (200-700 ng/g wet wt) than from fish taken elsewhere (<10 ng/g). Seventy to 90% of the DDT metabolites was DDE. Chlordane (3-13 ng/g) was analyzed in seven trout, six of them from central N.B. areas with intensive agriculture. Isomers of hexachlorocyclohexane were in highest concentration from north-central N.B. (10-20 ng/g), eastern N.S. (5-15 ng/g) and southern N.B. (5-20 ng/g). In most cases, alpha-hexachlorocyclohexane (lindane) was the isomer in highest concentration. Concentrations of hexachlorobenzene in fish tissues was highly variable with no obvious geographic bias. PCB’s were detected in very few fish, and no toxaphene was detected.

scholarly journals Distribution of flying insects across landscapes with intensive agriculture in temperate areas

2021 ◽  
Vol 129 ◽  
pp. 107889
Author(s):  
C.J.M. Musters ◽  
Tracy R. Evans ◽  
J.M.R. Wiggers ◽  
Maarten van 't-Zelfde ◽  
Geert R. de Snoo
Keyword(s):  
Intensive Agriculture ◽  
Flying Insects

Population Fluctuation and the Adoption of Food Production in Prehistoric Korea: Using Radiocarbon Dates as a Proxy for Population Change

Radiocarbon ◽  
2017 ◽  
Vol 59 (6) ◽  
pp. 1761-1770 ◽  
Author(s):  
Yongje Oh ◽  
Matthew Conte ◽  
Seungho Kang ◽  
Jangsuk Kim ◽  
Jaehoon Hwang
Keyword(s):  
Probability Distribution ◽  
Population Growth ◽  
Food Production ◽  
Population Change ◽  
Population Pressure ◽  
Population Fluctuation ◽  
Intensive Agriculture ◽  
Rice Farming ◽  
Radiocarbon Dates ◽  
Transition To Agriculture

AbstractPopulation growth has been evoked both as a causal factor and consequence of the transition to agriculture. The use of radiocarbon (14C) dates as proxies for population allows for reevaluations of population as a variable in the transition to agriculture. In Korea, numerous rescue excavations during recent decades have offered a wealth of14C data for this application. A summed probability distribution (SPD) of14C dates is investigated to reconstruct population trends preceding and following adoptions of food production in prehistoric Korea. Important cultivars were introduced to Korea in two episodes: millets during the Chulmun Period (ca. 6000–1500 BCE) and rice during the Mumun Period (ca. 1500–300 BCE). The SPD suggests that while millet production had little impact on Chulmun populations, a prominent surge in population appears to have followed the introduction of rice. The case in prehistoric Korea demonstrates that the adoption of food production does not lead inevitably towards sustained population growth. Furthermore, the data suggest that the transition towards intensive agriculture need not occur under conditions of population pressure resulting from population growth. Rather, intensive rice farming in prehistoric Korea began during a period of population stagnation.

Nitrogen from the atmosphere to the crop

1983 ◽  
Vol 12 (2) ◽  
pp. 90-97 ◽  
Author(s):  
P. P. King
Keyword(s):  
Large Scale ◽  
Crop Plants ◽  
Intensive Agriculture ◽  
Nitrogen Fixing ◽  
Biological Fixation ◽  
Traditional Methods ◽  
The Cost ◽  
Practical Implications

During the middle decades of this century large-scale intensive agriculture relied heavily on the availability of cheap synthetic nitrogenous fertilisers. Little attention then had to be paid to the cost of the energy involved in the manufacture and use of fertilisers, but in recent years this factor has become of major importance. This article reviews the practical implications of the energetics of chemical and biological fixation of nitrogen and the utilisation of nitrogen by various crop plants. It reaches a number of interesting conclusions, including one that even if biotechnology made nitrogen-fixing cereals available, they would not necessarily be competitive with normal cereals produced by traditional methods. This is, however, not necessarily true of grass.

Swamps, canals, and the locations of ancient Maya cities

Antiquity ◽  
1980 ◽  
Vol 54 (212) ◽  
pp. 206-214 ◽  
Author(s):  
R. E. W. Adams
Keyword(s):  
Radar Data ◽  
Classic Maya ◽  
Classic Period ◽  
Intensive Agriculture ◽  
Ancient Maya ◽  
Maya Lowlands ◽  
Rank Ordering ◽  
Topographic Information ◽  
Maya Civilization ◽  
Mapping Discovery

The recent radar mapping discovery of widely distributed patterns of intensive agriculture in the southern Maya lowlands provides new perspectives on classic Maya civilization. Swamps seem to have been drained, modified, and intensively cultivated in a large number of zones. The largest sites of Maya civilization are located on the edges of swamps. By combining radar data with topographic information, it is possible to suggest the reasons for the choice of urban locations. With the addition of patterns elicited from rank-ordering of Maya cities, it is also possible to suggest more accurate means of defining Classic period Maya polities.

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