Tillage and manure effect on soil physical and chemical properties and on carbon and nitrogen mineralization potentials

Abstract. Rice production is increasingly limited by water scarcity. Covering paddy rice soils with films (so-called ground cover rice production system: GCRPS) can significantly reduce water demand as well as overcome temperature limitations at the beginning of the growing season, which results in greater grain yields in relatively cold regions and also in those suffering from seasonal water shortages. However, it has been speculated that both increased soil aeration and temperature under GCRPS result in lower soil organic carbon and nitrogen stocks. Here we report on a regional-scale experiment conducted in Shiyan, a typical rice-producing mountainous area of China. We sampled paired adjacent paddy and GCRPS fields at 49 representative sites. Measured parameters included soil carbon (C) and nitrogen (N) stocks (to 1 m depth), soil physical and chemical properties, δ15N composition of plants and soils, potential C mineralization rates, and soil organic carbon (SOC) fractions at all sampling sites. Root biomass was also quantified at one intensively monitored site. The study showed that: (1) GCRPS increased SOC and N stocks 5–20 years following conversion from traditional paddy systems; (2) there were no differences between GCRPS and paddy systems in soil physical and chemical properties for the various soil depths, with the exception of soil bulk density; (3) GCRPS increased above-ground and root biomass in all soil layers down to a 40 cm depth; (4) δ15N values were lower in soils and plant leaves indicating lower NH3 volatilization losses from GCRPS than in paddy systems; and (5) GCRPS had lower C mineralization potential than that observed in paddy systems over a 200-day incubation period. Our results suggest that GCRPS is an innovative production technique that not only increases rice yields using less irrigation water, but that it also increases SOC and N stocks.

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Statistical criteria of stellar population types

Symposium - International Astronomical Union ◽

10.1017/s0074180900053304 ◽

1966 ◽

Vol 24 ◽

pp. 101-110

Author(s):

W. Iwanowska

Keyword(s):

Stellar Population ◽

Chemical Properties ◽

Spectrophotometric Study ◽

Physical And Chemical Properties ◽

Population Type ◽

The Galaxy ◽

Distribution Parameters ◽

Physical And Chemical ◽

Statistical Criteria ◽

And Chemical Properties

In connection with the spectrophotometric study of population-type characteristics of various kinds of stars, a statistical analysis of kinematical and distribution parameters of the same stars is performed at the Toruń Observatory. This has a twofold purpose: first, to provide a practical guide in selecting stars for observing programmes, second, to contribute to the understanding of relations existing between the physical and chemical properties of stars and their kinematics and distribution in the Galaxy.

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Only one sugar offers you such a variety of important physical and chemical properties

Chemical & Engineering News ◽

10.1021/cen-v037n007.p004 ◽

1959 ◽

Vol 37 (7) ◽

pp. 4

Keyword(s):

Chemical Properties ◽

Physical And Chemical Properties ◽

Physical And Chemical ◽

And Chemical Properties

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Response of corn (Zea mays L.) to various organic-based fertilizers in marginal upland of Sta. Rita, Samar

Annals of Tropical Research ◽

10.32945/atr39sa3.2017 ◽

2017 ◽

pp. 31-43

Author(s):

Berta Ratilla ◽

Loreme Cagande ◽

Othello Capuno

Keyword(s):

Block Design ◽

Management Strategies ◽

Chemical Properties ◽

Organic Fertilizers ◽

Growth And Yield ◽

Physical And Chemical Properties ◽

Total N ◽

Randomized Complete Block Design ◽

Physical And Chemical ◽

And Chemical Properties

Organic farming is one of the management strategies that improve productivity of marginal uplands. The study aimed to: (1) evaluate effects of various organic-based fertilizers on the growth and yield of corn; (2) determine the appropriate combination for optimum yield; and (3) assess changes on the soil physical and chemical properties. Experiment was laid out in Randomized Complete Block Design, with 3 replications and 7 treatments, namely; T0=(0-0-0); T1=1t ha-1 Evans + 45-30-30kg N, P2O5, K2O ha-1; T2=t ha-1 Wellgrow + 45-30-30kg N, P2O5, K2O ha-1; T3=15t ha-1 chicken dung; T4=10t ha-1 chicken dung + 45-30-30kg N, P2O5, K2O ha-1; T5=15t ha-1 Vermicast; and T6=10t ha-1 Vermicast + 45-30-30kg N, P2O5, K2O ha-1. Application of organic-based fertilizers with or without inorganic fertilizers promoted growth of corn than the control. But due to high infestation of corn silk beetle(Monolepta bifasciata Horns), its grain yield was greatly affected. In the second cropping, except for Evans, any of these fertilizers applied alone or combined with 45-30-30kg N, P2O5, K2O ha-1 appeared appropriate in increasing corn earyield. Soil physical and chemical properties changed with addition of organic fertilizers. While bulk density decreased irrespective of treatments, pH, total N, available P and exchangeable K generally increased more with chicken dung application.

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