Long term effect of inorganic fertilizers and organic manures on soil fertility status, microbial biomass carbon, and yield of rice on inceptisol

Long-term sodic-water irrigation may adversely affect the quality of soil organic carbon along with some soil properties. The extent to which the adverse effects can be ameliorated through the use of gypsum and amendments needs to be known. Soil properties and microbial biomass carbon (MBC) were studied after 14 years of sodic water (SW) irrigation and application of different levels of gypsum, farmyard manure (FYM), green manure (GM), and wheat straw (WS) to a sandy loam soil. Irrigation with SW increased pH, electrical conductivity, sodium adsorption ratio, exchangeable sodium percentage (ESP), and bulk density, and decreased final infiltration rate of soil. Application of gypsum and organic amendments reversed these trends. Decrease in MBC due to SW irrigation was from 132.5 to 44.6 mg/kg soil in the 0–75 mm soil layer and from 49.0 to 17.3 mg/kg soil in the 75–150 mm soil layer. Application of gypsum and organic amendments significantly increased MBC; GM and FYM were more effective than WS. Changes in soil ESP explained 85 and 75% variation in MBC in the unamended and organically amended SW treatments, respectively. Soil pH as additional variable improved the predictability of MBC to 96% and 77%. Irrigation with SW reduced yield of rice plus wheat by 5 t/ha. Application of gypsum and organic amendments significantly increased the rice and wheat yield; it was significantly correlated with MBC (r = 0.56**, n = 60). It confirms that MBC rather than organic C is a more sensitive indicator of environmental stresses in soils caused by long-term sodic water irrigation.

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Soil Microbial Biomass Carbon under Rhizosphere and Non- Rhizosphere of Maize after a Long-Term Nitrogen Fertilization and Tillage Systems

Journal of Tropical Soils ◽

10.5400/jts.2011.v16i1.63-68 ◽

2013 ◽

Vol 16 (1) ◽

pp. 63-68

Author(s):

. Dermiyati ◽

Eva Firdaus ◽

Muhajir Utomo ◽

Mas Achmad Syamsul Arif ◽

Sutopo Ghani Nugroho

Keyword(s):

Microbial Biomass ◽

Nitrogen Fertilizer ◽

Soil Microbial Biomass ◽

Microbial Biomass Carbon ◽

Maize Plant ◽

Biomass Carbon ◽

Tillage Systems ◽

Soil Microbial ◽

Soil Microbial Biomass Carbon

This research aimed to study the soil microbial biomass carbon (SMBC) under maize plant after a long-term application of nitrogen fertilizer and tillage systems (at the 37th growing season). The treatments were arranged in a factorial (3x3) in a randomized completely block design with 3 replications. The first factor was tillage systems, namely intensive tillage (IT) system, minimum tillage (MT) system, and no tillage (NT) system, and the second factor was the long-term application of nitrogen fertilizer, namely 0, 100, and 200 kg N ha-1. Data were analyzed using an orthogonal contrast test and a correlation test between SMBC and organic-C, total-N, and pH of the soil. The results showed that, in the rhizosphere and non-rhizosphere of maize plant, MT system increased the SMBC compared to NT and IT systems. However, application of long-term application of nitrogen fertilizer did not increase the SMBC. Nevertheless, fertilizer application of 100 kg N ha-1 increased the SMBC compare to 200 kg N ha-1.Furthermore, the combination of MT system and 100 kg N ha-1 could increase the SMBC compared to the other combined treatment between tillage systems and N fertilization doses. The SMBC was higher in the rhizosphere than in non-rhizosphere of maize plant.Keywords: Non-rhizosphere, rhizosphere, soil microbial biomass carbon, tillage systems

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