Sainju Upendra M, Lenssen Andrew W, Allen Brett L, Stevens William B, Jabro Jalal D
USDA, Agricultural Research Service, Northern Plains Agricultural Research Laboratory, 1500 North Central Avenue, Sidney, Montana 59270, USA.
Department of Agronomy, Iowa State University, Ames, IA 50011, USA.
Heliyon. 2017 Dec 28;3(12):e00481. doi: 10.1016/j.heliyon.2017.e00481. eCollection 2017 Dec.
Information on the long-term effect of management practices on soil C and N stocks is lacking. An experiment was conducted from 2004 to 2011 in the northern Great Plains, USA to examine the effects of tillage, crop rotation, and cultural practice on annualized crop residue (stems + leaves) returned to the soil and grain yield, and soil total C (STC) and total N (STN) stocks at the 0-120 cm depth. Tillage practices were no-tillage (NT) and conventional tillage (CT) and crop rotations were continuous spring wheat ( L.) (CW), spring wheat-pea ( L.) (W-P), spring wheat-barley ( L.) hay-pea (W-B-P), and spring wheat-barley hay-corn ( L.)-pea (W-B-C-P). Cultural practices were traditional (conventional seed rates and plant spacing, conventional planting date, broadcast N fertilization, and reduced stubble height) and improved (variable seed rates and plant spacing, delayed planting, banded N fertilization, and increased stubble height). Crop residue and grain yield were greater with CW and W-P than W-B-P and grain yield was greater with the traditional than the improved practice. The STC at 10-20 and 90-120 cm was greater with CW or W-P than other crop rotations in CT and greater with CW than W-B-P in NT. The STN at 20-40 cm was greater with W-P than CW and W-B-P in CT. With NT and the improved cultural practice, STN at 0-5, 5-10, 20-40, and 60-90 cm was greater with W-P and W-B-C-P than other crop rotations. The STN at 0-10 cm correlated with annualized crop residue and grain yield (r = 0.94-0.97, ≤ 0.05). Increased crop residue returned to the soil increased soil C stock with CW and W-P and N stock with W-P, but removal of aboveground crop biomass for hay decreased stocks with W-B-P. Increased soil N stock had a beneficial effect on crop grain yield.
关于管理措施对土壤碳和氮储量的长期影响的信息尚缺。2004年至2011年在美国大平原北部开展了一项试验，以研究耕作、作物轮作和栽培措施对归还土壤的年化作物残茬（茎 + 叶）、谷物产量以及0至120厘米深度土壤总碳（STC）和总氮（STN）储量的影响。耕作措施为免耕（NT）和传统耕作（CT），作物轮作为连作春小麦（L.）（CW）、春小麦 - 豌豆（L.）（W - P）、春小麦 - 大麦（L.）干草 - 豌豆（W - B - P）以及春小麦 - 大麦干草 - 玉米（L.） - 豌豆（W - B - C - P）。栽培措施为传统措施（传统播种量和株距、传统播种日期、撒施氮肥以及降低留茬高度）和改良措施（可变播种量和株距、延迟播种、条施氮肥以及增加留茬高度）。CW和W - P处理的作物残茬和谷物产量高于W - B - P，且传统措施下的谷物产量高于改良措施。在CT处理中，10至20厘米和90至120厘米深度处，CW或W - P处理的STC高于其他作物轮作，在NT处理中，CW处理的STC高于W - B - P。在CT处理中，20至40厘米深度处，W - P处理的STN高于CW和W - B - P。在NT和改良栽培措施下，0至5厘米、5至10厘米、20至40厘米以及60至90厘米深度处，W - P和W - B - C - P处理的STN高于其他作物轮作。0至10厘米深度处的STN与年化作物残茬和谷物产量相关（r = 0.94 - 0.97，≤ 0.05）。归还土壤的作物残茬增加，CW和W - P处理的土壤碳储量增加，W - P处理的土壤氮储量增加，但将地上作物生物量用作干草会降低W - B - P处理的储量。土壤氮储量增加对作物谷物产量有有益影响。
