生物属性视角下江苏省耕地产量与耕地质量现状及瓶颈分析

耕地质量一直是粮食生产的重中之重,近年来,我国耕地质量处于持续下降趋势。为深入分析我国现阶段耕地质量以此得出相应对策,文章基于生物属性视角,以江苏省为例,利用国家统计局相关数据从耕地产量与有机物情况、耕地产量与重金属情况、耕地产量与土地类型这3个方面进行深入探讨,从而分析江苏省耕地质量现状及存在的瓶颈,以此提出相应的政策建议。

Combining Ridge with No-Tillage in Lowland Rice-Based Cropping System: Long-Term Effect on Soil and Rice Yield

A tillage method of combining ridge with no-tillage (RNT) was employed in lowland rice-based cropping system to study the long-term effects of RNT on soil profile pattern, soil water stable aggregate distribution, nutrients stratification and yields of rice and post-rice crops. After flooded paddy field (FPF) was practiced with RNT for a long time, soil profile changed from G to A-P-G, and horizon G was shifted to a deeper position in the profile. Also the proportion of macroaggregate (> 2 mm) increased, whereas the proportion of silt and clay (< 0.053 mm) decreased under RNT, indicating a better soil structure that will prevent erosion. RNT helped to control leaching and significantly improved total N, P, K and organic matter in soil. The highest crop yields were found under RNT system every year, and total crop yields were higher under conventional paddy-upland rotation tillage (CR) than under FPF, except in 2003 and 2006 when serious drought occurred. RNT was proven to be a better tillage method for lowland rice-based cropping system.

Effects of improved fallow with Sesbania sesban on maize productivity and Striga hermonthica infestation in Western Kenya

Striga hermonthica is a major constraint to smallholder sub-sistence agriculture production in the sub-Saharan African region. Low soil fertility and overall environmental degradation has contributed to the build-up of the parasitic weed infestation. Improved cropping systems have to be introduced to address the interrelated problems of S. her-monthica and soil fertility decline. Thus, the effects of improved fallow with leguminous shrub Sesbania sesban on maize yields and levels of S. hermonthica infestation on farm land in the bimodal highlands of western Kenya were investigated. The experimental treatments were arranged in a phased entry, and randomized complete block scheme were six months Sesbania fallow, 18 months Sesbania fallow, six months natural fallow consisting of regrowth of natural vegetation without cultivation, 18 months natural fallow, continuous maize cropping without fertilizer application, and continuous maize cropping with P and N fertilization. Results show that Sesbania fallows significantly （p0.05） increase maize yield relative to continuous unfertilized maize. S. hermonthica plant populations decrease in continuous maize between the first season （mean = 428 000 ± 63 000 ha-1） and second season （mean=51 000 ± 15 000 ha-1）, presumably in response to good weed management. S. hermonthica seed populations in the soil decrease throughout the duration of the experi-ment in the continuous maize treatments. Short-duration Sesbania fal-lows can provide modest yield improvements relative to continuous unfertilized maize, but short-duration weedy fallows are ineffective. Continuous maize cultivation with good weed control may provide more effective S. hermonthica control than fallowing.

Sprinkler Irrigation and Soil Tillage Practices in Sugarcane Plantations as Influenced by Soil Texture and Water Storage in Northern Ivory Coast

Soil survey investigations were carried out in Ferk6 1 as well as Ferk6 2 sugar mills of northern Ivory Coast to determine soil texture and water storage capacity for sprinkler irrigation and tillage management. A 5-year term observation experiment on reduced tillage compared with conventional tillage was also conducted in Ferk6 1 over an irrigated cane crop of 28 ha for yield optimization purpose. Soil sampling was achieved after harvest or prior to re-plantation at five different spots along two transects over 30 cm depth in every farmland which covers about 30-40 ha with 432 m long cane rows as to get an average soil sample of 1.5-2 kg. Soil physical properties like texture and water retention curves were determined locally in the sugar company＇s soil laboratory. It came out that the majority of soils investigated was coarse-textured for about 64% in Ferk6 1 and 85% in Ferk6 2, with a lower to medium water storage capacity （70-89 mm） over 60 cm depth which corresponds to a readily available moisture less than 60 mm. Except for the sugarcane plant crop, no significant difference in cane yields resulting from tillage practices was observed over four consecutive cropping seasons. The yield decline from plant cane to first ratoon was very high under conventional tillage （-16 t/ha） compared with the reduced tillage （＋3 t/ha）. Even higher cane yield was obtained on the second ratoon （89 t/ha） compared with the conventional tillage （83 t/ha）.

Effect of Soil Erosion on Soil Properties and Crop Yields on Slopes in the Sichuan Basin,China

Roles of tillage erosion and water erosion in the development of within-field spatial variation of surface soil properties and soil degradation and their contributions to the reduction of crop yields were studied on three linear slopes in the Sichuan Basin,southwestern China.Tillage erosion was found to be the dominant erosion process at upper slope positions of each linear slope and on the whole short slope (20 m).On the long slope (110 m) and medium slope (40 m),water erosion was the dominant erosion process.Soil organic matter and soil nutrients in the tillage layer were significantly related to slope length and 137 Cs inventories on the long slope; however,there was no significant correlation among them on the short slope,suggesting that water erosion lowered soil quality by transporting SOM and surface soil nutrients selectively from the upper to lower slope positions,while tillage erosion transported soil materials unselectively.On the medium slope,SOM,total N,and available N in the tillage layer were correlated with slope length and the other properties were distributed evenly on the slope,indicating that water erosion on this slope was still the dominant soil redistribution process.Similar patterns were found for the responses of grain yield,aboveground biomass,and harvest index for slopes.These results indicated that tillage erosion was a major cause for soil degradation and grain yield reduction on the linear slopes because it resulted in displacement of the tillage layer soil required for maintaining soil quality and plant growth.