[Effects of different amounts of organic acid soil conditioners on soil nutrients and crop growth]. / ä¸åŒç”¨é‡æœ‰æœºé ¸åœŸå£¤è°ƒç†å‰‚å¯¹åœŸå£¤å »åˆ†å’Œä½œç‰©ç”Ÿé•¿çš„å½±å“.

Northwest China is burdened by declining soil fertility and poor capacity of water and nutrient retention. A pot experiment was conducted to examine the effects of organic acid conditio-ners (OASC) with four application rates (0, 20, 40, and 60 g·kg-1) on soil nutrients and crop growth. Maize and common vetch were the focus crops and loessial soil and irrigated desert soil were the soil types. The results showed that OASC application reduced water evaporation loss and significantly improved soil available nutrient content, with the most obvious effects on soil phosphorus. Available phosphorus content and proportion were increased by 256.5% and 227.4%, respectively, compared with no OASC treatment. The shoot dry weights of maize and common vetch on loessial soil were initially increased with the increasing OASC application rate and were highest at the application rate of 20 g·kg-1. The values progressively decreased with increasing OASC addition rates. Total salt content was significantly increased and the rate of emergence of common vetch decreased at OASC rate exceeding 20 g·kg-1. For irrigated desert soil, the OASC application rate did not affect total salt content when maize was planted. There was significant increase in soil total salt contents when common vetch was planted and at the OASC rate of 60 g·kg-1. The shoot dry weight of common vetch and maize was highest with the OASC application rates at 40 g·kg-1 and 60 g·kg-1, respectively. The optimal OASC rate for planting common vetch and maize on loess soil was 20 g·kg-1. The application rates of 40 g·kg-1 and 60 g·kg-1 were optimal for planting common vetch and maize on irrigated desert, respectively.

[Effects of no-tillage sowing with crop stubbles on seeding emergence and yield of spring wheat in Hexi Oasis Irrigated Area, Northwest China]. / ç•™èŒ¬å è€•æ’­ç§å¯¹æ²³è¥¿ç»¿æ´²çŒåŒºæ˜¥å°éº¦å‡ºè‹—å’Œäº§é‡çš„å½±å“.

We examined the effects of long-term no-tillage sowing with crop stubbles on seedling emergence quality and yield of spring wheat under the three typical spring wheat planting modes of single wheat, wheat-corn intercropping and wheat-soybean intercropping in a long-term field experiment in Hexi oasis irrigated area, aiming to provide theoretical support for the efficient and sustai-nable production of spring wheat. The results showed that, compared with traditional tillage, no-tillage sowing with crop stubbles significantly decreased seedling emergence rate and emergence evenness of spring wheat in wheat-corn intercropping and wheat-soybean intercropping by 3.3%-8.6%, 9.6%-20.5%, 2.9%-8.8%, and 10.7%-61.7%, respectively. Emergence evenness was significantly increased by 14.9% in 2019, while seedling emergence rate was significantly decreased by 4.2% in 2020 under the mode of single wheat compared with traditional tillage. Seedling uniformity of spring wheat seedling stage were reduced under the three typical planting modes, including single wheat, wheat-corn intercropping and wheat-soybean intercropping. Spike number of spring wheat were equal to that of traditional tillage at harvest under the three planting modes of no-tillage sowing with crop stubbles, and the differences were not significant. Effects of seedling emergence rate of spring wheat on yield was weakened by increasing grain number per spike and 1000-grain weight of spring wheat under the three planting modes. Grain yield was significantly increased by 10.3%-12.9% (single wheat), 10.5%-11.9% (wheat-corn intercropping), and 10.3%-22.5% (wheat-soybean intercropping) at harvest, respectively. Our results indicated that no-tillage sowing with crop stubbles was the feasible tillage mode in the production process of spring wheat in Hexi oasis irrigation area with extremely serious farmland wind erosion degradation.

Relationship of crop yield and soil organic carbon and nitrogen under long term fertilization in black loessial soil region on the Loess Plateau in China.

The feedbacks between crop yield and soil organic carbon and total nitrogen contents were examined in a long-term experiment, which was established on black loessial soil on the Loess Pla-teau in China. There were six treatments, including CK (no fertilizer), N (single nitrogen fertilizer), NP (chemical fertilizers NP), SNP (straw and chemical fertilizers NP), M (organic manure) and MNP (organic manure and chemical fertilizers NP). Results showed that balanced application of chemical fertilizers, single application of organic manure, the combined application of chemical fertilizers with organic manure and chemical fertilizers coupled with straw returning to the field all significantly increased crop yield and its stability compared with control (CK). The yields of maize and wheat in NP, SNP, M and MNP treatments increased by 92%, 97%, 93%, 141% and 147%, 164%, 139%, 214%, respectively, compared with the control. The annual mean yields of maize and wheat in NP treatment were equal to or higher than those of the local conventional fertilization practices and quite stable among different years, which indicated that the fertilization rates with N 90 kg·hm-2 and P2O5 75 kg·hm-2 were enough for crop growth in wheat-maize rotation system. Application of chemical fertilizer P every other year combined with straw returning to the field (SNP) had similar crop yield values with NP treatment, with the P application amount could be reduced by 50%. The balanced application of chemical fertilizers, organic manure application, the combined application of chemical fertilizers with organic manure, and chemical fertilizers coupled with straw returning to the field could significantly increase soil organic carbon content, whereas chemical fertilizer application had no significant influence on soil total nitrogen content. Across all treatments, the contents of soil organic carbon and total nitrogen were significantly and positively correlated. Under different fertilization treatments, organic carbon sequestration rate was between 15% and 41%. In SNP treatment, the soil organic carbon content enhanced 0.06 g·kg-1 when the amount of organic carbon input every increased 1 t·hm-2, while in CK, N, NP, M and MNP treatments, the increments was between 0.12 and 0.15 g·kg-1. The yields of both maize and wheat were positively correlated with soil total nitrogen content. Maize yield constantly increased with the increases of soil organic carbon content, but wheat yield increased at first and then kept stable with the increases of soil organic carbon content, with a threshold of 6.8 g·kg-1. In conclusion, long-term balanced application of chemical fertilizers, organic manure application, chemical fertilizers combined with manure and chemical fertilizers coupled with straw returning to the field could significantly increase soil organic carbon and total nitrogen contents, consequently resulted in higher crop yield and stubble amount returned to soil, the increase of stubble returned to soil further led to the increase of soil organic carbon and total nitrogen contents, which formed the mutual promotion feedback relationship each other in the black loessial soil region of Loess Plateau in China.

[Effects of long-term fertilization on nitrogen fertilizer use efficiency in loessial soil region on the Loess Plateau, Northwest China]. / 长期施肥对黄土高原黄绵土氮肥利用率的影响.

Nitrogen fertilizer use efficiency is a key parameter to determine recommended nitrogen fertilizer amount and evaluate the effects of nitrogen fertilizer application. The effects of long-term fertilization on annual and accumulated nitrogen fertilizer use efficiency and the relationship between them were studied using a 34-year fertilization experiment (1981-2015) in loessial soil region. The results showed that fertilization had significant influence on annual and accumulated nitrogen ferti-lizer use efficiency of wheat, rape and flax in the period of 1983-2015. The highest mean annual nitrogen fertilizer use efficiency of wheat was achieved in N, P and K combination (NPK), thesecond was N combined with P (NP), 77.7% and 62.0% higher than N application alone respectively. The highest mean annual nitrogen fertilizer use efficiency of rape was achieved in NPK, the second was manure (M), N, P and K combination (MNPK), 93.7% and 65.6% higher than N application alone respectively. The annual nitrogenfertilizer use efficiency of M combined with N (MN) increased significantly compared with N application alone. The annual nitrogen fertilizer use efficiency of M, N and P combination (MNP) decreased significantly compared with NP. The annual nitrogen fertilizer use efficiency of MNPK decreased significantly compared with NPK.There was significant positive linear relationship between annual nitrogen fertilizer use efficiency and crop yield. The correlation between accumulated nitrogen fertilizer use efficiency and crop yield was not significant. It indicated that the annual nitrogen fertilizer use efficiency could be more effective in representing fertilizer use efficiency characteristics under given soil fertility levels, crop varieties and environmental conditions compared with accumulated nitrogen fertilizer use efficiency.

[Soil Olsen-P content changing trend and its relationship with phosphorus surplus and crop yield under long-term fertilization in loessial soil region on the Loess Plateau, China]. / é•¿æœŸæ–½è‚¥é»„ç»µåœŸæœ‰æ•ˆç£·å«é‡æ¼”å˜åŠå ¶ä¸Žç£·ç´ å¹³è¡¡å’Œä½œç‰©äº§é‡çš„å ³ç³».

The changing trend of soil available phosphorus (Olsen-P) content in soil and its relationship with soil phosphorus surplus and crop yield are fundamental when making appropriate phosphate fertilizer recommendations. In this paper, the influences of long-term fertilization on crops phosphorus uptake, soil phosphorus surplus, changing trend of soil available phosphorus content and relationships of soil available phosphorus content with soil phosphorus surplus and crop yield were investigated through 34 years (1981-2015) long-term trial in loessial soil region on the Loess Plateau. The experiment had a completely-randomized-block split-plot design in triplicate. Two main-plot treatments were no farmyard manure and farmyard manure (M), and four subplot treatments were CK (no fertilizer), N (application of chemical fertilizer N), NP (application of chemical fertilizer NP) and NPK (balanced application of chemical fertilizer NPK), respectively. The results showed that fertilization treatments and crop types significantly influenced uptake amount of phosphorus and soil phosphorus surplus. Averaged over time from 1981 to 2015, wheat mean phosphorus uptake amounts of CK, N, NP, NPK, M, MN, MNP and MNPK were 8.63, 10.64, 16.22, 16.21, 16.25, 17.83, 20.39 and 20.27 kg·hm-2, while rape phosphorus uptakeamounts of eight treatments were 4.40, 8.38, 15.08, 15.71, 10.52, 11.23, 17.96 and 17.66 kg·hm-2, respectively. The surplus amount of soil phosphorus significantly correlated with the amount of phosphorus applied to soil. When soil phosphorus surplus amount equal zero, wheat and rape phosphorus input amounts were 10.47 kg·hm-2 and 6.97 kg·hm-2, respectively. Soil phosphorus surplus amount significantly influenced the changing trend of available phosphorus content in soil. CK and N treatments had no phosphorus input, and soil available phosphorus content exhibited a declining trend, annually decreased by 0.16 mg·kg-1 and 0.15 mg·kg-1, respectively. In contrast, NP, NPK, M, MN, MNP and MNPK six treatments were applied with phosphate fertilizer every years, and available phosphorus content gradually increased along with the duration of trial, with annual increase by 0.02-0.33 mg·kg-1. Soil available phosphorus content significantly correlated with phosphorus accumulative surplus amount, and the linear models were y=0.012x+9.33 and y=0.009x+11.72 in manure and no manure treatments, respectively. In no manure treatments, wheat yields significantly positively correlated with soil available phosphorus content, however, in manure treatments, their relationships did not reach a significant level. The relationship of wheat grain yield with available phosphorus content could be significantly fitted by piecewise linear model, and available phosphorus agronomy threshold of wheat was 14.99 mg·kg-1. Rape grain yield also increased with increasing soil available phosphorus content, but the relationship was not significant. This indicated when soil available P content is higher than 14.99 mg·kg -1, application of phosphate fertili-zer should be reduced or even avoided for planting wheat in loessial soil region on the Loess Plateau.