Jizong Zhang

Long-Term Application of Organic Manure and Mineral Fertilizer on N2O and CO2 Emissions in a Red Soil from Cultivated Maize-Wheat Rotation in China

Abstract A long-term field experiment was established to determine the influence of mineral fertilizer and organic manure on soil fertility. A tract of red soil (Ferralic Cambisol) in Qiyang Red Soil Experimental Station (Qiyang County, Hunan Province, China) was fertilized beginning in 1990 and N 2 O and CO 2 were examined during the maize and wheat growth season of 2007–2008. The study involved five treatments: organic manure (NPKM), fertilizer NPK (NPK), fertilizer NP (NP), fertilizer NK (NK), and control (CK). Manured soils had higher crop biomass, organic C, and pH than soils receiving the various mineralized fertilizers indicating that long-term application of manures could efficiently prevent red soil acidification and increase crop productivity. The application of manures and fertilizers at a rate of 300 kg N ha −1 yr −1 obviously increased N 2 O and CO 2 emissions from 0.58 kg N 2 O-N ha −1 yr −1 and 10 565 kg C ha −1 yr −1 in the CK treatment soil to 3.01 kg N 2 O-N ha −1 yr −1 and 28 663 kg C ha −1 yr −1 in the NPKM treatment. There were also obvious different effects on N 2 O and CO 2 emissions between applying fertilizer and manure. More N 2 O and CO 2 released during the 184-d maize growing season than the 125-d wheat growth season in the manure fertilized soils but not in mineral fertilizer treatments. N 2 O emission was significantly affected by soil moisture only during the wheat growing season, and CO 2 emission was affected by soil temperature only in CK and NP treatment during the wheat and maize growing season. In sum, this study indicates the application of organic manure may be a preferred strategy for maintaining red soil productivity, but may result in greater N 2 O and CO 2 emissions than treatments only with mineral fertilizer.

Preparation and utilization of phosphate biofertilizers using agricultural waste

Abstract In this study, Aspergillus niger 1107 was isolated and identified as an efficient phosphate-solubilizing fungus (PSF). This strain generated 689 mg soluble P L−1 NBRIP medium after 10 d of culture. To produce an affordable biofertilizer using A. niger 1107, the potential of widely available carrier materials for growth and maintenance of this strain were evaluated. The effects of sterilization procedures (autoclaving and gamma-ray irradiation) on the suitability of these carriers to maintain growth of the fungus were also investigated. The carrier materials were peat, corn cobs with 20% (w/w) perlite (CCP), wheat husks with 20% (w/w) perlite (WHP), and composted cattle manure with 20% (w/w) perlite (CCMP). In the first 5–6 mon of storage, the carriers sterilized by gamma-ray irradiation maintained higher inoculum loads than those in carriers sterilized by autoclaving. However, this effect was not detectable after 7 mon of storage. For the P-biofertilizer on WHP, more than 2.0×107 viable spores of A. niger g−1 inoculant survived after 7 mon of storage. When this biofertilizer was applied to Chinese cabbage in a pot experiment, there were 5.6×106 spores of A. niger g−1 soil before plant harvesting. In the pot experiment, Chinese cabbage plants grown in soil treated with peat- and WHP-based P-biofertilizers showed significantly greater growth (P

Row Ratios of Intercropping Maize and Soybean Can Affect Agronomic Efficiency of the System and Subsequent Wheat

Intercropping is regarded as an important agricultural practice to improve crop production and environmental quality in the regions with intensive agricultural production, e.g., northern China. To optimize agronomic advantage of maize (Zea mays L.) and soybean (Glycine max L.) intercropping system compared to monoculture of maize, two sequential experiments were conducted. Experiment 1 was to screening the optimal cropping system in summer that had the highest yields and economic benefits, and Experiment 2 was to identify the optimum row ratio of the intercrops selected from Experiment 1. Results of Experiment 1 showed that maize intercropping with soybean (maize || soybean) was the optimal cropping system in summer. Compared to conventional monoculture of maize, maize || soybean had significant advantage in yield, economy, land utilization ratio and reducing soil nitrate nitrogen (N) accumulation, as well as better residual effect on the subsequent wheat (Triticum aestivum L.) crop. Experiment 2 showed that intercropping systems reduced use of N fertilizer per unit land area and increased relative biomass of intercropped maize, due to promoted photosynthetic efficiency of border rows and N utilization during symbiotic period. Intercropping advantage began to emerge at tasseling stage after N topdressing for maize. Among all treatments with different row ratios, alternating four maize rows with six soybean rows (4M:6S) had the largest land equivalent ratio (1.30), total N accumulation in crops (258 kg ha-1), and economic benefit (3,408 USD ha-1). Compared to maize monoculture, 4M:6S had significantly lower nitrate-N accumulation in soil both after harvest of maize and after harvest of the subsequent wheat, but it did not decrease yield of wheat. The most important advantage of 4M:6S was to increase biomass of intercropped maize and soybean, which further led to the increase of total N accumulation by crops as well as economic benefit. In conclusion, alternating four maize rows with six soybean rows was the optimum row ratio in maize || soybean system, though this needs to be further confirmed by pluri-annual trials.

Optimizing the nitrogen application rate for maize and wheat based on yield and environment on the Northern China Plain

Optimizing the nitrogen (N) application rate can increase crop yield while reducing the environmental risks. However, the optimal N rates vary substantially when different targets such as maximum yield or maximum economic benefit are considered. Taking the wheat-maize rotation cropping system on the North China Plain as a case study, we quantified the variation of N application rates when targeting constraints on yield, economic performance, N uptake and N utilization, by conducting field experiments between 2011 and 2013. Results showed that the optimal N application rate was highest when targeting N uptake (240kgha-1 for maize, and 326kgha-1 for wheat), followed by crop yield (208kgha-1 for maize, and 277kgha-1 for wheat) and economic income (191kgha-1 for maize, and 253kgha-1 for wheat). If environmental costs were considered, the optimal N application rates were further reduced by 20-30% compared to those when targeting maximum economic income. However, the optimal N rate, with environmental cost included, may result in soil nutrient mining under maize, and an extra input of 43kgNha-1 was needed to make the soil N balanced and maintain soil fertility in the long term. To obtain a win-win situation for both yield and environment, the optimal N rate should be controlled at 179kgha-1 for maize, which could achieve above 99.5% of maximum yield and have a favorable N balance, and at 202kgha-1 for wheat to achieve 97.4% of maximum yield, which was about 20kgNha-1 higher than that when N surplus was nil. Although these optimal N rates vary on spatial and temporal scales, they are still effective for the North China Plain where 32% of Chinas total maize and 45% of Chinas total wheat are produced. More experiments are still needed to determine the optimal N application rates in other regions. Use of these different optimal N rates would contribute to improving the sustainability of agricultural development in China.

Spatio-temporal variations in organic carbon density and carbon sequestration potential in the topsoil of Hebei Province, China

Abstract Reliable prediction of soil organic carbon (SOC) density and carbon sequestration potential (CSP) plays an important role in the atmospheric carbon dioxide budget. This study evaluated temporal and spatial variation of topsoil SOC density and CSP of 21 soil groups across Hebei Province, China, using data collected during the second national soil survey in the 1980s and during the recent soil inventory in 2010. The CSP can be estimated by the method that the saturated SOC content subtracts the actual SOC associated with clay and silt. Overall, the SOC density and CSP of most soil groups increased from the 1980s to 2010 and varied between different soil groups. Among all soil groups, Haplic phaeozems had the highest SOC density and Endogleyic solonchaks had the largest CSP. Areas of soil groups with the highest SOC density (90 to 120 t C ha −1 ) and carbon sequestration (120 to 160 t C ha −1 ) also increased over time. With regard to spatial distribution, the north of the province had higher SOC density but lower CSP than the south. With respect to land-use type, cultivated soils had lower SOC density but higher CSP than uncultivated soils. In addition, SOC density and CSP were influenced by soil physicochemical properties, climate and terrain and were most strongly correlated with soil humic acid concentration. The results suggest that soil groups (uncultivated soils) of higher SOC density have greater risk of carbon dioxide emission and that management should be aimed at maximizing carbon sequestration in soil groups (cultivated soils) with greater CSP. Furthermore, soils should be managed according to their spatial distributions of SOC density and carbon sequestration potential under different soil groups.