水肥一体化下施氮量对土壤有机氮组分及玉米产量的影响

为进一步优化玉米水肥一体化施肥技术,促进氮肥有效转化利用,研究不同施氮量对土壤有机氮组分及玉米产量的影响。结果表明,随施氮量的增加,土壤酸解总氮、酸解铵态氮、酸解氨基酸态氮和酸解氨基糖态氮含量呈先上升后下降趋势,当施氮量为210 kg·hm^(-2)(N2处理)时,以上4种有机氮组分含量最高。酸解铵态氮是影响玉米产量的关键因素,N2处理下酸解铵态氮含量较N3(252 kg·hm^(-2))、N4(273 kg·hm^(-2))、N1(147 kg·hm^(-2))和N0(0 kg·hm^(-2))分别显著提高3.55%、9.86%、20.37%和170.21%;产量分别显著提高1.58%、2.97%、18.43%和112.89%。综上,N2处理(施氮肥210 kg·hm^(-2))具有更高的供氮潜力,是较为理想的施氮量。

Preface Global pioneers in soil conservation:Common elements and lessons learned

Introduction This Special Issue of the Journal of International Soil and Water Conservation Research is dedicated to those pioneers in soil conservation,farmers,researchers and extentionists,who questioned tradition and implemented new theories and new technologies in soil conservation.These pioneers recognized the often devastating impacts of agricultural land and soil degradation,and their observations of the impacts of intensive tillage and soil erosion led them to try new technologies such as zero till,no-till,direct seeding,stubble and residue mulching,and various other conservation tillage practices.Their successes are significant,because through these approaches,the pioneers laid the ecological foundation on which a more sustainable agriculture could be developed.

The transformation of agriculture in Argentina through soil conservation

The adoption of no till was a major turning point in the transformation of agriculture in Argentina.This paper describes the process of adoption of no till,and the impacts of this on agricultural production.Whereas previously,soil erosion was so extreme and pervasive as to threaten the economic viability and survival of the industry,today with the majority of production under no till,Argentina produces more than ever in the past.The paper also illustrates how,after first focusing on technology adoption(no-till),the system in Argentina has now broadened to include the concepts of Conservation Agriculture(CA)and Sustainable Land Management(SLM).These strategic moves have contributed to an agricultural industry in Argentina that is more economically and environmentally sustainable than that of the past.

No-till systems on the Chequen Farm in Chile:A success story in bringing practice and science together

No-till cropping systems provide an opportunity to protect the soil from erosion,while contemporaneously maintaining high yields and contributing to global food security.The historical aspects and the remarkable development of no-till systems on the Chequen Farm in Chile are reviewed.The adoption of no-till over the last 40 years has been a major turning point in reducing the devastating effects of soil erosion and a model for the evolution of sustainable crop production in highly erodible terrain in other parts of the world.The process of adoption of no-till systems in severely eroded foothills of Chile is described,as well as the environmental benefits and the sustainability of the system.The practical aspects of these developments are supported by scientific literature where appropriate,illustrating the value and coincident knowledge gained when combining analogue observations and information with scientific principles.