FERTILIZER MANAGEMENT

Transcription

1 FERTILIZER MANAGEMENT Long-Term Fertilization Effects on Crop Yield and Nitrate Nitrogen Accumulation in Soil in Northwestern China Shengmao Yang, Fengmin Li,* Sukhdev S. Malhi, Ping Wang, Dongrang Suo, and Jianguo Wang ABSTRACT tion of fertilization has reached 50 to 60% of the total A long-term (1982 to 2000) field experiment was conducted at increase in grain yields in China (Lu and Shi, 1998). Zhangye, Gansu, China, on a sandy clay loam (Typic Anthrosol) under Continued increases in agricultural production would wheat (Triticum aestivum L.) wheat corn (Zea mays L.) rotation to require increased supply of irrigation water as well as determine the effects of N, P, and K chemical fertilizers and farmyard fertilizers. However, some studies have shown that con- manure (M) on grain and straw yield, harvest index (HI), protein tinued use of inorganic fertilizers may result in destrucconcentration, and N uptake in grain and straw and accumulation of tion of soil structure and diminishing of quality and nitrate N (NO 3 N) in the soil profile (0 180 cm). The eight treatments productive capacity of soil (Lai et al., 1992; Doran et al., from various combinations of fertilizers and M were check, N, NP, 1996). Other studies have indicated negative (Jin and NPK, M, MN, MNP, and MNPK. Mean grain yield decreased in the Ma, 1996; Zhang et al., 2002), positive (Belay et al., 2002), order of MNPK MNP NPK MN NP M N check and no noticeable (Lu et al., 2001) effects on soil produc- (i.e., 8.01, 8.00, 7.51, 7.28, 7.00, 5.50, 4.89, and 3.43 Mg ha 1, respectivity. In most long-term experiments, combination of tively). Yield response to applied N and P increased with time since yields in the check plots declined with time. Potassium fertilizer appliyields in many parts of the world (Lin et al., 1996; Wang inorganic fertilizers and M has generally given the best cation provided no, slight, and dramatic increase in grain yield during the initial 6 yr, next 5 yr, and last 8 yr, respectively. Response of straw et al., 2002). yield to fertilizers and M was similar to the grain yield. Mean HI Statistics showed that N fertilizer consumption is growincreased with fertilizers in no-m treatments for both crops. Crude ing rapidly in the developing countries (Chalk et al., protein concentration and N uptake in grain and straw increased 2003). This has resulted in serious environmental consemarkedly with fertilizers, and M increased it further. Fertilizers (N, quences, such as NO 3 leaching and eutrophication (Zhu, NP, and NPK) led to NO 3 N accumulation in most subsoil layers. 1995; Ferguson et al., 1996; Matson et al., 1998). Overfer- Combined applications of fertilizers and M reduced soil NO 3 N accutilization can cause water, air, and soil pollution (Singh mulation in soil compared with fertilizers alone. In conclusion, the et al., 1995; Zhang et al., 1996; Carpenter et al., 1998; findings suggest that it is important to use balanced application of chemical fertilizers and M at proper rates in order to protect soil Mosier and Kroeze, 2000). Nitrate N leaching is a major and underground water from potential NO 3 N pollution while also problem for calcareous soils in which ammonium (NH 4 ) sustaining high crop production. is quickly nitrified to NO 3 (Tong et al., 1997). It has become a major concern worldwide, mainly due to increased N fertilizers and farmyard M inputs (Yuan et al., Soil management practices, such as tillage, irrigation, 2000; Di and Cameron, 2002; Zhu and Chen, 2002). The soil-mulching cultivation, and fertilization, usually problems of NO 3 leaching and the contamination of result in crop yield increases (Burgess et al., 1996; Ras- ground and surface waters exist widely in Europe, USA, mussen et al., 1997; Li et al., 1999, 2001). Among these China, and elsewhere (Spalding and Exner, 1993; Zhang agronomic measures, fertilization may be the most imand drinking water showed that 50% of the samples et al., 1996). In northern China, analysis of ground water portant way to maintain high crop productivity and soil quality (Suo and Wang, 2000; Shen, 2002). The contribu- had NO 3 content above the critical value (Zhang et al., 1995); and it was 21.5 and 29.7% for the Shaanxi and Guandong Provinces of China, respectively (Lu and Shi, S. Yang and F. Li, The Key Lab. of Arid and Grassl. Agroecol., Lanzhou 1998). Guillard et al. (1995) reported an increase of Univ., Ministry of Educ., Lanzhou, , P.R. China; J. Wang, Inst. NO 3 N in soil with increasing rate of N fertilizer. Nitroof Soil and Fert., Gansu Acad. of Agric. Sci., Lanzhou , P.R. China; S.S. Malhi, Agric. and Agri-Food Canada, Research Farm, gen fertilizer applied in excess of crop needs can cause P.O. Box 1240, Melfort, SK, Canada S0E 1A0; P. Wang, Gansu Agric. accumulation of NO 3 N in the soil profile (Malhi et al., Univ., Lanzhou , P.R. China; and D. Suo, Inst. of Agric. Sci. of 1991, 2002). Zhangye Prefecture, Zhangye , P.R. China. Contribution from The long-term approach to minimize movement of the Key Laboratory of Arid and Grassland Agroecology, Lanzhou NO 3 into groundwater is to develop site-specific im- University, Ministry of Education, Lanzhou, , P.R. China; Instiproved N fertilization and irrigation management practute of Soil and Fertilizer, Gansu Academy of Agricultural Sciences, Lanzhou , P.R. China; Gansu Agricultural University, Lanzhou tices to increase N uptake efficiency, decrease N loss, and , P.R. China; and Institute of Agricultural Sciences of Zhangye minimize leaching losses below the root zone. The objec- Prefecture, Zhangye , P.R. China. Received 22 July *Cor- tive of this study was to determine the effects of chemical responding author (fmli@lzu.edu.cn). fertilizers and farmyard M on grain and straw yield, HI, Published in Agron. J. 96: (2004). American Society of Agronomy 677 S. Segoe Rd., Madison, WI USA Abbreviations: HI, harvest index; M, manure. 1039

2 1040 AGRONOMY JOURNAL, VOL. 96, JULY AUGUST 2004 protein concentration, N uptake in grain and straw, and cultivar of corn was Hudan no. 1, Yedan 476, and Hudan no. 1 accumulation of NO 3 N in the soil profile. in 1984, 1987, and 1990, and Zhongdan no. 2, Shendan no. 10, and Zhongdan no.16 in 1993, 1997, and Spring wheat MATERIALS AND METHODS was seeded in mid-march at a rate of 300 kg ha 1, and corn was planted at a rate of seeds ha 1 in mid- to late April. A field experiment was conducted from 1982 to 2000 on a The row spacing was 15 cm for wheat and 50 cm for corn. All calcareous desert soil (sandy clay loam, mixed, Typic Anthroseven plots were irrigated three to four times for wheat and six to sol) near Zhangye (38 36 N, E; 1560 m altitude) in times for corn during each growing season. The irriga- Hexi Corridor of Gansu Province in northwestern China. This tion was implemented when soil moisture was depleted to region is one of the main grain production areas in China. 45% of field capacity. The amount of each irrigation was 53 Mean annual precipitation is 136 mm, and mean temperature to 67 mm of water. is 7.0 C. Annual potential evaporation is about 1990 mm. Anby Grain and straw yields of wheat and corn were determined nual frost-free period is about 165 d, and approximately 50% hand harvesting of plants from central rows (14 rows har- of the annual precipitation is received during July to Septemuse vested for wheat and six rows harvested for corn). Nitrogen ber. At the experimental site, mean annual precipitation during efficiency was expressed as kg grain kg 1 applied N ha 1. the study period was 127 mm (range of 72 mm in 1985 to Harvest index was calculated by dividing grain yield by grain 214 mm in 1983), and on average, 53% (range of 36% in 1987 plus straw yield. Grain and straw samples were dried at 55 C, to 85% in 1995) of the annual precipitation was received in ground to pass a 0.3-mm sieve, and analyzed for total N Kjel- July to September. Mean annual air temperature at this site dahl N (Bremner, 1965a) to determine the concentration of ranged from 6.3 to 9.5 C. Mean monthly temperatures ranged crude protein. Protein (crude) concentration was calculated from 19.8 to 23.2 C for July, 18.9 to 21.8 C for August, and by multiplying total N concentration by 5.70 for wheat grain 13.3 to 17.5 C for September. Soil test results from the experiof and by 6.25 for wheat straw, corn grain, and corn straw. Uptake mental site in 1982 were 8.4 ph, 20.8 g kg 1 organic matter, N in grain (or straw) was calculated by multiplying yield 28.1 mg kg 1 available N (NO 3 N NH 4 N), 21.7 mg kg 1 of grain (or straw) by percentage N in grain (or straw). After extractable P (0.5 M NaHCO 3 ), and 99.1 mg kg 1 exchangeable corn harvest in 2000, soil samples from each plot (five compos- K(1M NH 4 CH 3 COO). ite samples or cores per plot) were collected from the 0- to 20-, Twenty-four plots (each plot 6.6 by 5.0 m in size) in a splitdepths. The soil samples were air-dried, ground to pass a 2-mm 20- to 60-, 60- to 100-, 100- to 140-, and 140- to 180-cm soil plot factorial included eight treatments and three replications. Adjacent plots were separated by ridges (50-cm width), and sieve, and analyzed for NO 3 N using Cd reduction method the blocks were separated by irrigation furrows (60-cm width) (Bremner, 1965b). The data were subjected to analysis of and two ridges (50-cm width). Main-plot treatments were with variance (SAS Inst., 1989). Differences among treatments M and without M, and subplot treatments consisted of unfertil- were determined with least significant difference (LSD) at the ized check, N, NP, and NPK. The eight treatments were check, 0.05 probability level. Cumulative yields were regressed using N, NP, NPK, M, MN, MNP, and MNPK. The inorganic fertilizer linear regressions. sources of N, P, and K, respectively, were ammonium ni- trate or urea, single superphosphate or diammonium phosphate, RESULTS AND DISCUSSION and potassium chloride commercial fertilizers. The majority of farmyard M was swine M, which is extensively used by the Grain Yield, Straw Yield, and Harvest Index local farmers. The nutrient analyses of M varied from year to The cumulative grain yields over the 19-yr period year, but on the average, farmyard M contained 29.1 g kg 1 organic matter, 1.5 g kg showed generally consistent trends of increased re- total N, 0.88 g kg 1 total P, 34 g kg 1 total K, mg kg 1 available N (NH 4 N NO 3 N), 60.3 mg sponses to chemical fertilizers and M with time (Fig. 1 kg 1 extractable P, and 1293 mg kg 1 exchangeable K. and 2). The linear correlations between cumulative grain Nitrogen fertilizer was applied at 120 and 150 kg N ha 1 to yields and years were highly significant. This indicated wheat during and , respectively, and at that the yield responses to applied fertilizers and M had 240, 300, and 450 kg N ha 1 to corn during , 1991 similar patterns over years. The differences between 1999, and 2000, respectively. Half of N fertilizer was applied linear graphs from various chemical fertilizers and M to wheat as base fertilizer 1 d before sowing, and the other treatments increased as experiment progressed. The cuhalf was broadcast at three-leaf stage. For corn, 30, 30, and mulative grain yield was 65.17, 92.84, , , 40% of the N fertilizer was applied at sowing, jointing/elonga , , , and Mg ha 1, respectively, tion, and 10- to 12-leaf (pretasseling) stages, respectively. Rates of P and K fertilizers, respectively, were 26 to 33 kg P for the check, N, NP, NPK, M, MN, MNP, and MNPK. ha 1 and 50 to 63 kg K ha 1 for wheat and 53 to 99 kg P ha 1 The mean cumulative grain yield was Mg ha 1 and 101 to 189 kg K ha 1 for corn. Farmyard M (with average greater for the M plots than the no-m plots (Fig. 2). moisture content of 15%) was applied at 60 and 75 t ha 1 to Manure-alone treatment (M) produced 73% grain yield both wheat and corn during (8.4 kg ha 1 available of that with NPK. N, 77.0 kg ha 1 total N, 3.6 kg ha 1 available P, 52.5 kg ha 1 On the average of all years, among the chemical fertiltotal P, 77.1 kg ha 1 available K, and kg ha 1 total K) izer treatments, maximum grain yield was obtained with and (10.4 kg ha 1 available N, 96.2 kg ha 1 total NPK for both crops. The MNP treatment gave greater N, 4.5 kg ha 1 available P, 65.6 kg ha 1 total P, 96.4 kg ha 1 yield than NPK, and in the M plots, there was little or available K, and kg ha 1 total K), respectively. All of no increase in yield from K application. The trends of the M, P, and K fertilizer were applied before sowing as basal dressing (i.e., mixed evenly to a depth of 15 cm with plowing). maximum grain yield with NPK in no-m plots and with The experiment rotation was wheat wheat corn. The wheat MNPK or MNP in M plots were similar for both crops cultivars were Zhangchun no. 9, Zhangchun no. 11, and Zhangfor corn. The average grain yield for wheat was 2.23, though percentage increase was greater for wheat than chun in the first 10 yr ( ) and Zhangchun no. 20 and Zhangchun 920 in the later 9 yr ( ). The 3.29, 5.08, 5.44, 3.46, 5.24, 5.82, and 5.82 Mg ha 1, respec-

3 YANG ET AL.: LONG-TERM FERTILIZATION EFFECTS ON CROP AND SOIL 1041 Fig. 1. Regressions of cumulative grain yield (kg ha 1 ) of crops with years in wheat wheat corn rotation from , treated annually with various combinations of N, P, and K fertilizers and unfertilized check, without and with manure (M) on a calcareous sandy loam soil under irrigation near Zhangye, Gansu, China (LSD 0.05 for differences between all treatments is 4.451). Fig. 2. Regressions of mean cumulative grain yield (kg ha 1 ) of crops with years in wheat wheat corn rotation from , treated annually with various combinations of N, P, and K fertilizers and unfertilized check, without manure (UM) and with manure (M) on a calcareous sandy loam soil under irrigation near Zhangye, Gansu, China (LSD 0.05 for differences between main-plot treatments is 3.420).

4 1042 AGRONOMY JOURNAL, VOL. 96, JULY AUGUST 2004 tively, for the check, N, NP, NPK, M, MN, MNP, and NPK compared with NP in no-m treatments only. From MNPK. In the same order, the average grain yield for , grain yield of both M and no-m treatments corn was 6.02, 8.34, 11.15, 12.00, 9.91, 11.69, 12.70, and generally increased significantly with K fertilization Mg ha 1. Mean grain yield in the M plots was Until 1993, the maximum grain yield was attained with greater than no-m plots by 1.08 Mg ha 1 for wheat and the MNP treatment. From , the maximum 2.39 Mg ha 1 for corn. grain yield was attained when K fertilizer was also ap- The order of cumulative or average grain yield was plied. Extractable K in the soil decreased from 99 mg MNPK MNP NPK MN NP M N Kkg 1 in 1982 to 56 mg K kg 1 in 2000 in the NP fercheck. This showed that the highest crop yield in the tilizer treatment. Thus, the grain yield difference between present study was obtained when both chemical fertilizers NPK and NP treatment became evident after 6 and M were applied together. Our results agree with yr without M and after four rotations with M. This the findings of other researchers who also attained the indicated that without K fertilizer application, inher- best crop yield with combined applications of chemical ently K-rich calcareous desert soil in Gansu would become fertilizers and M (Lal and Mathur, 1989; Kabeerathumma deficient in K after 6 and 12 yr, without and with et al., 1993; Lin et al., 1996; Vats et al., 2001; M application, respectively. Wang et al. (2003) found Wang et al., 2002). This is most likely because M improves decrease in the K-supplying capacity of soil with zero- soil physical properties (Lal and Mathur, 1989; K application for 11 yr. Our findings suggest that pro- Kurual and Tripathi, 1990) and provides stable supply ducers, who are using high rates of N and P fertilizers, of both macro- and micronutrients (Kabeerathumma et must pay attention to the K fertility of soils for sustainable al., 1993) and thus supports the maximum yield. crop production in these K-rich soils. For example, The lowest grain yield was obtained in no-fertilizer M can provide a stable supply of K to crops under check plots. As the experiment progressed, grain yields intensive cropping systems (Kumar et al., 2000). in the check treatment generally decreased. Grain yield Various fertilizers affected grain yields differently in of corn in the check in 2000 (2.615 Mg ha 1 ) was only various rotation periods (data not shown). The grain 28.2% of that measured in 1984 (9.260 Mg ha 1 ), and yield increasing effect of N fertilization apparently enlarged wheat grain yield in 1999 (1.610 Mg ha 1 ) was 33.7% as the experiment progressed. Application of N of that attained in 1982 (4.780 Mg ha 1 ). This indicates fertilizer increased grain yield by 13.2 to 21.1% in the that soil productivity decreased with time, most likely first to third rotation periods and by 65.9 and 95.2% in due to depletion in soil fertility (Kumar et al., 2000). the fourth and fifth rotation periods. In the first 6 yr For both the M and no-m treatments, the yield response ( ), grain yield showed moderate response to to applied N increased with years since the yield M application (Fig. 2). From , grain yield of of the check plots decreased significantly during the both wheat and corn increased markedly with M appli- experimental period, as earlier observed by Jin and Ma cation. The application of M increased grain yield by (1996). However, grain yield decreased in the N treatment 5.0 to 5.3% in the first two rotation periods and by 19.5 for both crops as the experiment progressed. Also, to 58.5% in the following four rotation periods. This the positive effect of P, K, and M applications became showed that M had cumulative effect during the dura- more evident in later years of the experiment, clearly tion of the experiment. This is in agreement with the showing that N alone was unable to maintain crop productivity previous findings in the black soil in northeastern China and soil quality to sustain high crop yield. (Zhang et al., 2000; Liu et al., 2001). Furthermore, cumu- Addition of P fertilizer increased grain yield, and the lative residual effect of M in the present study was yield response to applied P for both with- and without-m greater than that of 9.8, 7.6, and 7.0%, respectively, in treatments increased substantially with time. This suggests the no-fertilizer, N-alone, and NP treatments of a 13-yr that the soil became deficient in available P with experiment reported by Liu et al. (2001). This was prob- time, as evidenced by decline in extractable P in the ably related to the difference in organic matter content soil from 22 mg P kg 1 in 1982 to 4 mg P kg 1 in 2000 in in the two soils, which was much higher (54.0 g kg 1 )in the N treatment. In another long-term experiment on the black soil (Liu et al., 2001) than that in the calcareous a calcareous soil in northeast China, crops did not re- desert soil of the present study (29.1 g kg 1 ). spond to P fertilizer during the first 3 yr, but significant The average of data from all years showed that appli- yield response was obtained in later years (Zhang et al., cation of N increased crop yields by 42.4 and 32.4% in 2000). The response of grain yield to P fertilization was the no-m and M treatments, respectively. In the presrelatively less in M treatments. This was most probably ence of N fertilizer, P application increased grain yield due to that M contained P which became available to by 43.2 and 9.9% in the no-m and M treatments, respec- crops (Vats et al., 2001). In addition to check, grain tively. The K fertilization increased grain yield by 7.4% yield in the N and NP treatments also decreased dramatically when no M was used and by only 2.7% when M was in the last 7 yr. This suggests that soil became used. The reduced yield response to applied fertilizers deficient in nutrients other than N and P with time and with time in the M treatments compared with no-m N and P fertilizers were not enough to sustain high treatments was most likely due to availability of these grain yields. nutrients to crop plants in the growing season in M There was no grain yield response by either crop to plots. Based on the 19-yr data (13 seasons of wheat and K fertilizer application in the first 6 yr from six seasons of corn), grain yield increase from different From , grain yield tended to be greater with fertilizers followed an order of N M P K, with

5 YANG ET AL.: LONG-TERM FERTILIZATION EFFECTS ON CROP AND SOIL 1043 Fig. 3. Harvest index (ratio of grain yield to grain straw yield) of crops from , treated annually with various combinations of N, P, and K fertilizers and unfertilized check, without and with manure on a calcareous sandy loam soil under irrigation near Zhangye, Gansu, China (LSD 0.05 for differences between main-plot treatments is for wheat and for corn; LSD 0.05 for differences among subplot treatments is for wheat and for corn). the average grain yield increase over check of 36.2, 26.2, creased with application of chemical fertilizers in both 23.3, and 3.6%, respectively. without- and with-m treatments. Application of M-only Straw yield was determined in 10 of the 19 yr from increased HI over check plot in all 3 yr, but M had no 1988 to The response of straw yields to fertilizer effect on HI in the plots receiving chemical fertilizers. and M applications was similar to the grain yields, and For the average of HI in different rotation periods, thus straw yields are not presented here. On average, chemical fertilizers and/or M did not show any increase straw yield for wheat was 3.47, 5.64, 8.60, 9.22, 5.56, 8.98, of HI in the and rotation periods and Mg ha 1, respectively, for the check, N, But in , HI increased from in the check NP, NPK, M, MN, MNP, and MNPK. The correspond- to 0.42 in N, 0.43 in NP, and 0.46 in NPK treatment. ing straw yield for corn was 6.68, 9.88, 14.62, 15.50, 12.50, Application of M alone increased HI to 0.42 in the M 15.30, 16.93, and Mg ha 1. The mean straw yield treatment. This indicates that M has long-term cumulafor no-m and M treatments, respectively, was 6.73 and tive residual effect on grain yield (Zhang et al., 2000) 8.84 Mg ha 1 for wheat and and Mg ha 1 for corn. and subsequently increased HI in the present study. Harvest index (ratio of grain yield to grain straw Protein Concentration in Grain and Straw yield) was determined in 10 of the 19 yr (1988 to 1997), in which both grain and straw yields were recorded. Concentration of protein (crude) was determined in Mean HI increased with application of chemical fertiliz- 7 yr (i.e., 1987, 1988, 1989, 1990, 1991, 1995, and 2000). ers in no-m plots for both crops (Fig. 3). For wheat, Concentration of protein in grain increased consider- M-only plots had greater HI than that of check, and ably with chemical fertilizers in all years, and M treatthere was no further increase in HI from chemical fertil- ments further increased it (Fig. 4). For the average of izers. For corn, M-only treatment did not increase HI 7 yr, protein concentration in wheat grain was 98.3, compared with check, but application of chemical fertilrespectively, 116.0, 118.0, 112.4, 112.4, 131.1, 126.3, and g kg 1, izers increased HI. This was probably due to higher N for the check, N, NP, NPK, M, MN, MNP, requirements of corn than that of wheat for the maxiprotein and MNPK treatments. The corresponding values for mum yield. The mean HI for wheat was 0.36, 0.38, 0.40, concentration in corn grain were 59.2, 82.3, 95.6, 0.41, 0.41, 0.40, 0.39, and 0.39 for check, N, NP, NPK, 96.3, 85.0, 99.2, 95.4, and 90.8 g kg 1. For the average M, MN, MNP, and MNPK, respectively. In the same of both crops, protein concentration in grain was inorder, the HI values for corn were 0.40, 0.43, 0.43, 0.44, creased by 20.0 and 21.3%, respectively, with N and NP 0.40, 0.43, 0.44, and In the first 7 yr ( ), compared with check. Addition of K to NP declined there was usually no increase in HI with application of protein concentration in grain slightly, most probably chemical fertilizers, except in 1990 for corn (data not due to the dilution effect from the increased yield with shown). Application of M increased HI in 3 of 7 yr in K fertilizer. The mean protein concentrations in grain the check treatment, but application of M in combinaand for no-m and M treatments, respectively, were tion with chemical fertilizers did not cause any further g kg 1 for wheat and 83.3 and 92.6 g kg 1 for increase in HI. In the last 3 yr (1995 to 1997), HI in- corn. The concentration of protein in grain was thus

6 1044 AGRONOMY JOURNAL, VOL. 96, JULY AUGUST 2004 Fig. 4. Concentration of protein (g protein kg 1 ) in grain of crops from , treated annually with various combinations of N, P, and K fertilizers and unfertilized check, without and with manure on a calcareous sandy loam soil under irrigation near Zhangye, Gansu, China (LSD 0.05 for differences between main-plot treatments is 2.8 for wheat and 1.9 for corn; LSD 0.05 for differences among subplot treatments is 9.3 for wheat and 11.0 for corn). improved with M application by 11.2% over check, with respectively, for the check, N, NP, NPK, M, MN, MNP, slightly higher value for wheat (12.3%) than that for and MNPK treatments. For corn, the corresponding N corn (9.0%). The results on protein in grain suggested uptake in grain straw was 103.6, 212.9, 253.3, 281.8, that fertilizer and M applications could result in better 176.5, 275.2, 299.7, and kg N ha 1. Mean N uptake quality grain (Malhi et al., 1999) in addition to improving in grain straw was greater in M plots than in no-m grain and straw yield. plots (180.6 vs kg N ha 1 for wheat and vs. Concentration of protein in straw increased with kg N ha 1 for corn). Other researchers have also chemical fertilizers in 4 of the 7 yr, and it increased reported significant improvement in nutrient uptake by further in 3 of the 7 yr when M was applied in combina- crop when farmyard M was applied in addition to chemition with chemical fertilizers (data not shown). For the cal fertilizers (Lal and Mathur, 1989). The relative difaverage of 7 yr, protein concentration in wheat straw ferences among fertilized treatments were greater for was 18.0, 19.7, 23.3, 24.1, 19.1, 34.2, 39.3, and 33.1 g kg 1, crop N uptake than for yield due to increase in both respectively, for the check, N, NP, NPK, M, MN, MNP, yield and concentration of N in grain and straw with and MNPK treatments. In the same order, protein con- fertilizer application. In both M and no-m treatments, centrations in corn straw were 23.3, 35.6, 33.3, 39.2, 30.2, N uptake in grain and straw was greater with N and NP 41.9, 40.8, and 41.0 g kg 1. The mean protein concentra- compared with check. Addition of K to NP increased tions in straw for no-m and M treatments, respectively, N uptake slightly in grain or straw in the no-m plots, were 21.3 and 31.4 g kg 1 for wheat and 32.9 and 38.5 g but in the M plots, there was no increase in N uptake kg 1 for corn. For the average of both crops, there was in grain or straw (in fact, there was a slight decrease in some increase of protein concentration in straw with N uptake). This was most likely due to decline in total M-only application compared with the check treatment N concentration in grain and straw, probably because of (by 18.8%). Similar to grain, the relative increase of dilution effect from the increased yield with K fertilizer. protein concentration in straw from M application was The average N uptake in wheat grain was 35.2, 71.7, higher (by 38.2%) for wheat than for corn (by 17.0%) , 113.4, 74.3, 133.9, 137.2, and kg N ha 1, This difference was due to lower straw yield for wheat respectively, for the check, N, NP, NPK, M, MN, MNP, than for corn. and MNPK treatments. The corresponding values for corn grain were 71.9, 134.1, 176.1, 194.6, 127.7, 191.3, Uptake of Nitrogen and Recovery of Applied 199.4, and kg N ha 1. The average N uptake in Nitrogen in Grain and Straw grain was greater in M plots than in no-m plots (121.7 The N uptake increased considerably in grain and vs kg N ha 1 for wheat and vs kg N straw with chemical fertilizers in all years, and M treatwas ha 1 for corn). On average, N uptake in wheat straw ments increased it further, but the results on N uptake 13.6, 24.0, 41.5, 42.6, 21.1, 60.9, 82.8, and 70.9 kg N in grain straw are only presented in this report (Fig. 5). ha 1, respectively, for the check, N, NP, NPK, M, MN, The total N uptake in wheat grain straw was 48.8, MNP, and MNPK treatments. In the same order, N 95.6, 149.6, 155.9, 95.5, 194.8, 220.0, and kg N ha 1, uptake in corn straw was 31.7, 78.8, 77.2, 87.2, 48.8, 83.8,

7 YANG ET AL.: LONG-TERM FERTILIZATION EFFECTS ON CROP AND SOIL 1045 Fig. 5. Total N uptake (kg N ha 1 ) in grain straw of crops from , treated annually with various combinations of N, P, and K fertilizers and unfertilized check, without and with manure on a calcareous sandy loam soil under irrigation near Zhangye, Gansu, China (LSD 0.05 for differences between main-plot treatments is 16.9 for wheat and 18.5 for corn; LSD 0.05 for differences among subplot treatments is 17.6 for wheat and 12.8 for corn) , and 87.8 kg N ha 1. Mean N uptake in straw was M for 19 yr (Fig. 6). Sole application of N fertilizer greater in M plots than in no-m plots (58.9 vs kg increased NO 3 N in the soil profile only slightly com- Nha 1 for wheat and 80.2 vs.68.7 kg N ha 1 for corn). pared with the check treatment. Earlier, Campbell et al. The N uptake in grain was much greater for corn than (1994) found that fertilized wheat had more NO 3 N for wheat, in spite of lower concentration of total N in accumulation in the 0- to 120-cm soil depth than that corn than in wheat. This was due to greater grain yield of the unfertilized wheat. However, in present study, for corn than wheat. application of N in combination with P and/or with K Without M, the recovery of applied chemical fertilizer fertilizers (NP and NPK) had markedly greater NO 3 N N in grain was increased considerably with application accumulation in the soil profile compared with N alone. of P fertilizer in combination with N, and it was in- This is not consistent with earlier results that higher creased further when K was also applied along with NP amounts of NO 3 N accumulated in the N and NP treat- (data not shown). With M, the N recovery from ap- ments compared with 100% NPK and the NO 3 N accuplication of P and K fertilizers in combination with N mulation was inversely related to cumulative N uptake increased slightly for wheat but decreased for corn. by the crops (Benbi and Biswas, 1997). This displayed Mean recovery of applied fertilizer N in wheat grain that in spite of much lower crop yields with N alone was 26.8, 53.6, 57.5, 43.8, 46.2, and 49.1%, respectively, than NP or NPK, there was no buildup of NO 3 N in for the N, NP, NPK, MN, MNP, and MNPK treatments. soil in the N treatment and substantial buildup of NO 3 N For corn, the corresponding values for N recovery in in soil in the NP or NPK treatments. The findings of grain were 21.1, 35.3, 41.6, 21.6, 24.3, and 17.9%. The mean recoveries of applied N in grain in no-m and M another study showed that the loss of NO 3 N under plots were similar for wheat (46.0 vs. 46.4%), but for arable soil system ranged from 4 to 107 kg N ha 1, with corn, the N recovery was greater in the no-m treatment an average value of 37.8 kg N ha 1 when N was applied than in the M treatment (32.7 vs. 21.3%). The recovery no more than 200 kg N ha 1 yr 1 (Di and Cameron, of applied N in straw showed a trend similar to grain. 2002). Because of low yields resulting in low uptake of The average recovery of applied N in wheat straw was N, buildup of NO 3 N was expected in the N alone treat- 7.6, 20.5, 21.3, 29.2, 45.4, and 36.6%, respectively, for ment, but this did not happen in the present study. The the N, NP, NPK, MN, MNP, and MNPK treatments. possible reason may be that the applied N transformed The corresponding values for N recovery in corn straw into N 2,NH 3, or other organic N form lost from the were 16.0, 15.4, 18.8, 11.9, 17.5, and 13.2%. Unlike grain, soil plant system. This suggests that further research is mean recoveries of applied N in straw were less in no-m needed to determine the fate of applied N in the future. treatment than in the M treatment for wheat (16.5 vs. In the NP and NPK treatments, NO 3 N changed mod- 37.1%), but for corn, the N recoveries in straw were erately in the 0- to 20-cm soil depth (by 0.51 to 2.88 mg similar in no-m and M treatments (16.7 vs. 14.2%). kg 1 ) but increased drastically in the 20- to 180-cm layers. Nitrate Nitrogen in Soil Profile The NO 3 N accumulation peak mostly occurred at the 60- to 100-cm soil depth (15.3 to 28.5 mg kg 1 ) and Mass of NO 3 N in soil profile was significantly influenced below that soil depth, it decreased gradually. However, by annual applications of various fertilizers and NO 3 N accumulation was markedly less in NPK treat-

8 1046 AGRONOMY JOURNAL, VOL. 96, JULY AUGUST 2004 Fig. 6. Nitrate N mass (kg N ha 1 ) in different soil layers after 19 annual applications ( ) of various combinations of N, P, and K fertilizers and unfertilized check, without and with manure on a calcareous sandy loam soil under irrigation near Zhangye, Gansu, China (for the 0- to 20-, 20- to 60-, 60- to 100-, 100- to 140-, and 140- to 180-cm depths, respectively, the LSD 0.05 for differences between main-plot treatments is 0.6, 5.7, 8.1, 7.2, and 8.9, and the LSD 0.05 for differences among subplot treatments is 1.5, 7.7, 9.6, 4.9, and 7.3). ment than in the NP treatment. Previous work has treatments, respectively. Therefore, the amount of N shown that balance application of N, P, and K fertilizers not accounted for was much greater in the N alone could reduce NO 3 N accumulation in the deeper soil treatment than in the other treatments. This also indi- (Darusman et el., 1991; Sun et al., 1999). In the present cated that there were large amounts of unaccounted N study, findings with long-term annual applications of N, in the M plots, in spite of marked increase in crop yield P, and K fertilizers at the used rates suggested potential and N uptake with M. This was most likely due to the for harmful effect to soil and groundwater quality. reason that a portion of the organic N in M did not The NO 3 N mass was less with MNP or MNPK com- mineralize and did not become available to crops, as pared with NP or NPK (Fig. 7). Similar findings have evidenced by higher concentration of total N in the been made in other long-term experiments (Tong et al., 0- to 20-cm soil depth in 2000 in M plots than in no-m 1997; Yang et al., 1998; Laegreid et al., 1999). Nitrate plots (mean total N content of 0.144% with M vs. N accumulation in soil caused by M happened in only the 0.101% without M). It is also possible that a portion of MN treatment. This suggests that when M was applied the mineralized N from M may have been lost from together with N and P and/or with K fertilizers (MNP the soil plant system as gaseous N (Meek et al., 1982; and MNPK), it decreased NO 3 N accumulation in soil Lessard et al., 1996). significantly. The results on N not accounted for indicated that the amount of applied N in the present experiment Nitrogen Uptake in Crop, Nitrate Nitrogen substantially exceeded that required to attain optimum in Soil, and Nitrogen Balance crop production. Previously, researchers have shown For all treatments, approximate N balances were deor avoided and the potential danger of groundwater or that the accumulation of NO 3 N in soil can be reduced termined to include amount of N applied, N uptake in crop, and NO 3 N recovered in the soil profile (Table 1). atmospheric pollution can be minimized by using N rates The estimated total N uptake in grain straw was 1256, below or equal to the N amount needed for the optimum 2522, 3465, 3719, 2299, 4183, 4659, and 4366 kg N ha 1, crop yield (Malhi et al., 1997, 2003). This also suggests respectively, in the check, N, NP, NPK, M, MN, MNP, and that a portion of the applied N not accounted for may MNPK treatments (Table 1). The corresponding values have moved below the 180-cm soil depth and/or possibly of N applied in chemical fertilizer plus M during the been lost from the soil plant system through denitrifica- 19-yr experimental period were 0, 3540, 3540, 3540, 1850, tion (e.g., nitrous oxide and other N gases) due to wet 5390, 5390, and 5390 kg N ha 1. The amounts of N that soil conditions, which temporarily existed under flood could not be accounted for from the chemical N fertilizer irrigation in the present study. This can pose a potential and M were 2262, 1096, 762, 789, 2351, 1903, and 2217 risk for contamination of underground water and to the kgnha 1 in the N, NP, NPK, M, MN, MNP, and MNPK atmosphere (e.g., depletion of ozone layer and global

9 YANG ET AL.: LONG-TERM FERTILIZATION EFFECTS ON CROP AND SOIL 1047 Fig. 7. Nitrate N mass (kg N ha 1 ) in the 0- to 180-cm soil depth after 19 annual applications ( ) of various combinations of N, P, and K fertilizers and unfertilized check, without and with manure on a calcareous sandy loam soil under irrigation near Zhangye, Gansu, China (LSD 0.05 for differences between main-plot treatments is 5.3; LSD 0.05 for differences among subplot treatments is 13.3). warming). In Canada, research has shown that applica- cal fertilizers (Fig. 6). Other researchers have also reported tion of high rates of hog M in addition to inorganic N increase in concentrations of residual NO 3 N fertilizer can cause water pollution due to accumulation in soil profile at high N rates in various cropping systems of NO 3 N in soil (Gangbazo et al., 1999). The amount (Malhi et al., 1991, 2002; Guillard et al., 1995). of N applied in this experiment was close to the fertilizer Soil NO 3 N below the effective root zone of crops is N normally applied by farmers in this region of China. susceptible to leaching, and the loss of NO 3 N through Total amounts of NO 3 N recovered in the 0- to 180-cm deep percolation can result in N contamination of groundwater soil depth were 10, 16, 247, 325, 28, 122, 94, and 73 kg with irrigation and can have a potential risk to Nha 1 in the check, N, NP, NPK, M, MN, MNP, and groundwater quality and soil health (Zhang et al., 1996; MNPK treatments, respectively. This indicated that annual Vasconcelos et al., 1997; Yuan et al., 2000). applications of chemical fertilizers and M over a The amounts of NO 3 N in soil with and without M period of 19 yr had a considerable effect on the amounts treatments indicated that M applied with chemical fertil- of NO 3 N accumulated in the soil profile. There was izers could markedly reduce NO 3 N accumulation in substantial movement of NO 3 N to the depth of 180 cm the soil profile while also increasing crop yields. The find- sampled in this study, especially in plots receiving chemi- ings suggest that to reduce the risk of downward move- Table 1. Balance sheet of N applied to wheat wheat corn rotation from (kg ha 1 ), treated annually with various combinations of N, P, and K fertilizers and unfertilized check, without and with manure (M) on a calcareous sandy loam soil under irrigation near Zhangye, Gansu, China. Amount of N Parameter Check N NP NPK M MN MNP MNPK kgnha 1 Nitrate N recovered in soil (0 180 cm) in N removed in grain in 19 yr N removed in straw in 19 yr N removed in grain straw (plant) in 19 yr Total N recovered in soil plant Total N recovered in soil plant from N fertilizer and manure Mineral N applied in chemical N fertilizer Mineral N applied in manure Organic N applied in manure Total N applied in fertilizer manure Unaccounted N balance (total applied N total N recovered in soil plant from N fertilizer and manure) % Unaccounted N as percentage of applied N Estimated from mean values of yield and total N concentration in grain and straw for wheat and corn. Fertilized and/or manure plots check.

10 1048 AGRONOMY JOURNAL, VOL. 96, JULY AUGUST 2004 ment of NO 3 N out of rooting zone, M should be applied Burgess, M.M., G.R. Mehuys, and C.A. Madrammootoo Tillage and crop residue effects on corn production in Quebec. Agron. in a combination with N, P, K, and other fertilizer nutri- J. 88: ents lacking in the soil. But, it is also necessary to apply Campbell, C.A., G.P. Lafond, R.P. Zentner, and Y.W. Jame M and chemical fertilizers at proper rates to protect soil, Nitrate leaching in an Udic Haploboroll as influenced by fertilization underground water, and the atmosphere from potential and legumes. J. Environ. Qual. 23: NO Carpenter, S.R., N.F. Caraco, D.L. Correll, R.W. Howarth, A.N. 3 N pollution while also sustaining high crop yields. Sharpley, and V.H. Smith Nonpoint pollution of surface waters with phosphorus and nitrogen. Ecol. Appl. 8: CONCLUSIONS Chalk, P.M., L.K. Heng, and P. Moutonnet Nitrogen fertilization and its environmental impact. p In L. Ji, G. Chen, E. During 19 yr, grain yield in the no-fertilization treatmillenium fertilizer, Schnug, C. Hera, and S. Hanklaus (ed.) Fertilization in the third food security and environmental protection. ment (check) declined, and yield response to applied Vol. 1. Proc. Int. World Fert. Congr., 12th, Beijing, China. 3 9 fertilizer and M treatments increased with time. The Aug Sci. and Technol. Press of Liaoning, Shenyang, China. impact of fertilizers on grain yields was N M P Darusman, L.R. Stone, and K.A. Whitney Soil properties after K. The K fertilizer showed no grain yield increasing 20 years of fertilization with different nitrogen sources. Soil Sci. effect in the initial 6 yr, and its effect on grain yield Soc. Am. J. 55: increased as the experiment progressed. Based on the Di, H.J., and K.C. Cameron Nitrate leaching in temperate agroecosystems: Sources, factors and mitigating strategies. Nutr. 19-yr data, the grain yields decreased in the order of Cycling Agroecosyst. 46: MNPK MNP NPK MN NP M N Doran, J.W., M. Sarrantonio, and M.A. Liebig Soil health and check. Generally, the response of straw yield to fertilizer sustainability. Adv. Agron. 56:1 54. treatments was similar to grain yield. Mean HI increased Ferguson, A.J.D., M.J. Pearson, and C.S. Reynolds Eutrophica- with application of chemical fertilizers in no-m plots for tion of natural water and toxic algal blooms. Issues Environ. Sci. Technol. 5: both crops, but application of M alone increased HI Gangbazo, G., G.M. Barnett, A.R. Pesant, and D. Cluis Disposover check for wheat. Manure alone plots usually had ing hog manure on inorganically-fertilized corn and forage fields greater HI than check, especially for wheat. Chemical in southeastern Quebec. Can. Agric. Eng. 41:1 12. fertilizers and M significantly increased protein concen- Guillard, K., G.F. Griffin, D.W. Allinson, W.R. Yamartino, M.M. tration and N uptake in grain and straw. From the point Rafey, and S.W. Pietryzk Nitrogen utilization of selected cropping systems in the U.S. Northeast: II. Soil profile nitrate of increasing crop yield and quality, MNPK was the distribution and accumulation. Agron. J. 87: best treatment. Fertilization of wheat and corn for 19 Jin, S., and Y. Ma Effect of long-term fertilization on crop yield successive years had a marked effect on NO 3 N accumu- and soil fertility. p In B. Lin, J. Lin, and J. Li (ed.) lation in the soil profile. Accumulation of NO 3 N in Changes of crop yield and soil fertility by long-term fertilization. Chinese Agric. Sci. and Technol. Press, Beijing. the 20- to 140-cm depth soil profile with application Kabeerathumma, S., C.R. Mohankumar, G.M. Nair, and P.G. Nair. of inorganic fertilizers (NP and NPK) is considered a Effect of continuous cropping of cassava with organics and potential danger for pollution to soil environment as inorganics on the secondary and micronutrient elements status of well as the groundwater. Compared with the chemical an Ultisol. J. Indian Soc. Soil Sci. 41: fertilizers alone, the application of M along with the Kumar, R., G. Singh, and S.S. Walia Long term effect of manure and fertilizers on rice yield and soil fertility status in rice wheat commercial fertilizers (MN, MNP, and MNPK treatsystem. Environ. Ecol. 18: ments) reduced residual soil NO 3 N to some extent. Kurual, A., and R.P. Tripathi Effect of continuous use of ma- The findings suggest that it is necessary to use balanced nures and fertilizers on physical properties of soil under paddy application of chemical fertilizers and M at proper rates wheat cowpea cropping system. Crop Res. 3:7 12. to protect soil and underground water from potential Laegreid, M., O.C. Bockman, and O. Kaarstad Nitrogen. p In Agriculture, fertilizers and the environment. CABI NO 3 N pollution while sustaining high crop production. Publ. and Norsk Hydro ASA, Wallingford, Oxon, UK. Lai, Q., C. Li, and Q. Huang Effect of continuous application ACKNOWLEDGMENTS of inorganic fertilizer on soil structure properties of paddy soil derived from red soil. Acta Pedol. Sin. 29: This research was partly supported by NKBRSF Project Lal, S., and B.S. Mathur Effect of long-term fertilization, manur- G , National Important Basic Research Pre-Arrange- ing and liming of an Alfisol on maize, wheat and soil properties: ments Special Project, NSFC (Grant no ), International I. Maize and wheat. J. Indian Soc. Soil Sci. 37: Foundation for Science (C/3571-1), and Gansu Foundation for Lessard, R., P. Rochette, E.G. Gregorich, E. Patty, and R.L. 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