Fertilization effects on yield sustainability and soil properties under irrigated wheat–soybean rotation of an Indian Himalayan upper valley

To date, the sustainability of wheat (Triticum aestivum)–soybean (Glycine max) cropping systems has not been well assessed, especially under Indian Himalayas. Research was conducted in 1995–1996 to 2004 at Hawalbagh, India to study the effects of fertilization on yield sustainability of irrigated wheat–soybean system and on selected soil properties. The mean wheat yield under NPK + FYM (farmyard manure) treated plots was ~27% higher than NPK (2.4 Mg ha⁻¹). The residual effect of NPK + FYM caused ~14% increase in soybean yield over NPK (2.18 Mg ha⁻¹). Sustainable yield index values of wheat and the wheat–soybean system were greater with annual fertilizer N or NPK plots 10 Mg ha⁻¹ FYM than NPK alone. However, benefit:cost ratio of fertilization, agronomic efficiency and partial factor productivity of applied nutrients were higher with NPK + FYM than NPK, if FYM nutrients were not considered. Soils under NPK + FYM contained higher soil organic C (SOC), total soil N, total P and Olsen-P by ~10, 42, 52 and 71%, respectively, in the 0–30 cm soil layers, compared with NPK. Non-exchangeable K decreased with time under all treatments except NPK. Total SOC in the 0–30 cm soil layer increased in all fertilized plots. Application of NPK + FYM also improved selected soil physical properties over NPK. The NPK + FYM application had better soil productivity than NPK but was not as economical as NPK if farmers had to purchase manure.     

Long-term effect of fertilizer and manure application on soil-carbon sequestration and soil fertility under the wheat–wheat–maize cropping system in northwest China

Maintenance of soil organic carbon (SOC) is important for the long-term productivity of agroecosystems. An investigation was conducted to study the effects of long-term application of inorganic fertilizers and farmyard manure (FYM) on soil organic carbon (SOC), nitrogen, phosphorus, and potassium nutrient content, water-stable aggregate distribution, and aggregate-associated carbon in a field experiment started in 1982 in an arid region of northwest China. Application of inorganic fertilizer alone (N, NP, or NPK treatments) did not increase SOC concentrations compared with no application of fertilizers (CK) and SOC concentration was significantly reduced, by 18% on average, compared with the initial value at the beginning of the experiment. Application of imbalanced inorganic fertilizer (N and NP), especially, resulted in a significant decrease in available phosphorus and potassium nutrients at a depth of 20 cm. This indicates that long-term application of inorganic fertilizers were inadequate to maintain levels of SOC and nutrients under conventional management with no aboveground crop residues returning to the soil. Long-term application of FYM alone or combined with inorganic fertilizers (M (FYM), MN, MNPK, or MNPK treatments), however, improved SOC and total nitrogen concentrations from initial values of 12.1 and 0.76 g kg⁻¹, respectively, to 15.46 and 1.28 g kg⁻¹, on average, and also enhanced available nitrogen, phosphorus, and potassium concentrations by 47, 50, and 68%, respectively, during the 23-year period. Treatment with FYM resulted in a 0.48 mm greater average mean weight diameter (MWD) of aggregates and a higher percentage of macro-aggregates (>2 mm) and small macro-aggregates (2–0.25 mm) than treatment without FYM. The MWD increased with increasing SOC concentration (R ²=0.75). The SOC concentration was highest in small macro-aggregates, intermediate in macro-aggregates, and lowest in micro-aggregates (0.25–0.05 mm). Approximately 54–60% of total SOC was stored in micro-aggregates (0.25–0.05 mm) and sand+silt fractions (<0.05 mm) after treatment without FYM but 57–64% of total SOC was stored in macro-aggregates (>0.25 mm) after treatment with FYM. MNPK treatment had the greatest effect on improving the levels of SOC and NPK nutrients and in enhancing the formation and stability of macro-aggregates.     

Greenhouse gas intensity and net annual global warming potential of cotton cropping systems in an extremely arid region

A long-term fertilizer experiment investigating cotton-based cropping systems established in 1990 in central Asia was used to quantify the emissions of CO₂, CH₄ and N₂O from April 2012 to April 2013 to better understand greenhouse gas (GHG) emissions and net global warming potential (GWP) in extremely arid croplands. The study involved five treatments: no fertilizer application as a control (CK), balanced fertilizer NPK (NPK), fertilizer NPK plus straw (NPKS), fertilizer NPK plus organic manure (NPKM), and high rates of fertilizer NPK and organic manure (NPKM+). The net ecosystem carbon balance was estimated by the changes in topsoil (0–20 cm) organic carbon (SOC) density over the 22-year period 1990–2012. Manure and fertilizer combination treatments (NPKM and NPKM+) significantly increased CO₂ and slightly increased N₂O emissions during and outside the cotton growing seasons. Neither NPK nor NPKS treatment increased SOC in spite of relatively low CO₂, CH₄ and N₂O fluxes. Treatments involving manure application showed the lowest net annual GWP and GHG intensity (GHGI). However, overuse of manure and fertilizers (NPKM+) did not significantly increase cotton yield (5.3 t ha^?1) but the net annual GWP (?4,535 kg CO₂_eqv. ha^?1) and GHGI (?0.86 kg CO₂_eqv. kg^?1 grain yield of cotton) were significantly lower than in NPKM. NPKS and NPK slightly increased the net annual GWP compared with the control plots. Our study shows that a suitable rate of fertilizer NPK plus manure may be the optimum choice to increase soil carbon sequestration, maintain crop yields, and restrict net annual GWP and GHGI to relatively low levels in extremely arid regions.     

Carbon sequestration in soil aggregates under different crop rotations and nitrogen fertilization in an inceptisol in southeastern Norway

Effects of crop rotation and fertilization (nitrogen and manure) on concentrations of soil organic carbon (SOC) and total soil nitrogen (TSN) in bulk soil and in soil aggregates were investigated in a long-term field experiment established in 1953 at Ås, Norway. The effect of these management practices on SOC sequestration was estimated. The experiment had three six-course rotations: (I) continuous spring grain, (II) spring grain for 3 years followed by root crops for 3 years, and (III) spring grain for 2 years followed by meadow for 4 years. Three fertilizer treatments compared were: (A) 30–40 kg N ha^–1; (B) 80–120 kg N ha^–1; and (C) a combination of B and 60 Mg farmyard manure (FYM) ha^–1. All plots received a basal rate of PK fertilizer. Soil samples from these treatments were collected in autumn 2001 and analyzed for aggregate size, SOC and TSN concentrations. There were significant increases in 0.6–2 mm and < 0.6 mm aggregate size fractions, and reduction in the 6–20 mm and the > 20 mm sizes for rotation III only. There were also significant differences among rotations with regard to water stable aggregation. The order of increase in stability was II < I < III. Fertilizer treatment had no effect on aggregation or aggregate size distribution, but there was a slight tendency of increased stability with the application of FYM. Aggregate stability increased with increasing concentration of SOC (r2 = 0.53). The SOC and TSN concentrations in bulk soil were significantly higher in rotation III than in rotations II and I. Application of FYM increased SOC and TSN concentrations significantly in the 0–10 cm soil depth, but there were few significant differences between fertility treatments A and B. There was a trend of increase in concentration of SOC and TSN with decreasing aggregate size, but significant differences in these parameters in different aggregate size fractions were found only in few cases. The SOC and TSN concentrations were higher in >0.25 mm than in < 0.25 mm aggregates. The SOC sequestration rate was 77–167 kg SOC ha^–1 yr^–1 by increasing the N rate and 40–162 kg SOC ha^–1 yr^–1 by applying FYM. The SOC sequestration rate by judicious use of inorganic fertilizer was the greatest in the grain–meadow rotation, while that by application of FYM was the greatest in the all grain rotation.     

Response of dryland wheat to fertilizer nitrogen in relation to stored water,rainfall and residual farm yard manure

Yield response of dryland wheat to fertilizer N application in relation to components of seasonal water (available soil moisture and rainfall) and residual farm yard manure (FYM) was studied for five years (1983–84 to 1987–88) on a maize-wheat sequence on sandy loam soils in Hoshiarpur district of Punjab, India. Four rates of N viz. 0, 40, 60 and 80 kg ha^–1 in wheat were superimposed on two residual FYM treatments viz. no FYM (F₀) and 15 t ha^–1 (F₁₅) to preceding maize. FYM application to maize increased the residual NO₃-N content by 19–30 kg ha^–1 in the 180 cm soil profile. For a given moisture distribution, F₁₅ increased attainable yields. Over the years, F₁₅ increased wheat yield by 230 to 520 kg ha^–1. Response to fertilizer N was lower in FYM amended plots than in unamended plots. Available soil moisture at wheat seeding and amount and distribution of rainfall during the vegetative and the reproductive phases of crop development affected N use efficiency by wheat. Available soil moisture at seeding alone accounted for 50% variation in yield. The residual effect of FYM on wheat yield could be accounted for by considering NO₃-N in 180 cm soil profile at seeding. The NO₃-N and available soil moisture at wheat seeding along with split rainfall for two main phases of crop development and fertilizer N accounted for 96% variation in wheat yield across years and FYM treatments.     

Crop yield, nitrogen uptake and nitrate-nitrogen accumulation in soil as affected by 23 annual applications of fertilizer and manure in the rainfed region of Northwestern China

Application of chemical fertilizers and farmyard manure affects crop productivity and improves nutrient cycling within soil–plant systems, but the magnitude varies with soil-climatic conditions. A long-term (1982–2004) field experiment was conducted to investigate the effects of nitrogen (N), phosphorus (P), and potassium (K) fertilizers and farmyard swine manure (M) on seed and straw yield, protein concentration, and N uptake in the seed and straw of 19-year winter wheat (Triticum aestivum L.) and four-year oilseed (three-year canola, Brassica napus L. in 1987, 2000 and 2003; one-year flax, Linum usitatisimum L. in 1991), accumulation of nitrate-N (NO₃-N) in the soil profile (0–210 cm), and N balance sheet on a Huangmian soil (calcaric cambisols, FAO) near Tianshui, Gansu, China. The two main plot treatments were without and with farmyard swine manure (M); sub-plot treatments were control (Ck), N, NP, and NPK.␣The average seed yield decreased in the order MNPK ≥ MNP > MN ≥ NPK ≥ NP > M > N > Ck. The average effect of manure and fertilizers on seed yield was in the order M > N > P > K. The seed yield increase was 20.5% for M, 17.8% for N, 14.2% for P, and 2.9 % for K treatment. Seed yield response to fertilizers was much greater for N and P than for K, and it was much greater for no manure than for manure treatment. The response of straw yield to fertilization treatments was usually similar to that of seed yield. The N fertilizer and manure significantly increased protein concentration and N uptake plant. From the standpoint of increasing crop yield and seed quality, MNPK was the best fertilization strategy. Annual applications of N fertilizer and manure for 23 successive years had a marked effect on NO₃-N accumulation in the 0–210 cm soil profile. Accumulation of NO₃-N in the deeper soil layers with application of N fertilizer and manure is regarded as a potential danger, because of pollution of the soil environment and of groundwater. Application of N fertilizer in combination with P and/or K fertilizers reduced residual soil NO₃-N significantly compared with N fertilizer alone in both no manure and manure plots. The findings suggest that integrated and balanced application of N, P, and K fertilizers and␣manure at proper rates is important for protecting soil and groundwater from potential NO₃-N pollution and for maintaining high crop productivity in the rainfed region of Northwestern China.     

Improving nutrient use efficiency from decomposing manure and millet yield under Plinthosols in Niger

To improve synchronicity between nutrients released from the decomposing manure with millet nutrient requirement under zaï technique, a 2-year field experiment was conducted at the International Crops Research Institute for the Semi-Arid Tropics Research Station, Sadoré, Niger. The treatments consisted of factorial combination of two rates of cattle manure (200 and 300 g per zaï hole), three periods of manure application (before planting, at planting and 15 days later) and two rates of mineral fertilizer [nitrogen (N), phosphorus (P) and potassium (K) 15–15–15] applied at 6 g per zaï hole and a control, without mineral fertilizer). Manure dry mass losses did not significantly differ among manure application periods in 2013. However, in 2014 the highest manure dry mass loss occurred when manure was applied before planting with 70% of manure applied being decomposed at millet maturity stage (115 days after litterbag installation) followed by manure applied at planting with almost 50% of dry mass losses. The quantities of N and P absorbed by millet at tillering stage represented, 61, 52 and 33% of N released and 15, 12 and 15% of P released at the same time when manure was applied before planting, at planting and 15 days after planting, respectively. Application of manure before planting increased on an average millet grain yield by 16 and 20% and N utilization efficiency by 25 and 31% compared to application of manure at planting and 15 days after planting respectively. Addition of mineral fertilizer induced a synergetic effect on millet grain yield (p = 0.002). Millet grain yields increased on average by 5, 17 and 57% when 6 g per zaï pit of NPK fertilizer were added to plots receiving manure application before planting, at planting and 15 days after planting, respectively. We conclude that application of manure prior to planting satisfies better millet nutrients demand, thereby increasing nutrient use efficiency and grain yield under zai pits.     

Crop yields and soil organic carbon fractions as influenced by straw incorporation in a rice–wheat cropping system in southeastern China

In agro-ecosystems, the relationship between soil fertility and crop yield is mediated by manure application. In this study, an 8-year field experiment was performed with four fertilizer treatments (NPK, NPKM₁, NPKM₂, and NPKM₃), where NPK refers to chemical fertilizer and M₁, M₂, and M₃ refer to manure application rates of 15, 30, and 45 Mg ha^?1 year^?1, respectively. The results showed that the NPKM (NPKM₁, NPKM₂, and NPKM₃) treatments produced greater and more stable yields (4.95–5.45 Mg ha^?1 and 0.59–0.75) than the NPK treatment (4.01 Mg ha^?1 and 0.50). Crop yields under the NPKM treatments showed two trends, with a rate of decrease of 0.48–0.83 Mg ha^?1 year^?1 during the first 4 years and a rate of increase of 0.10–0.25 Mg ha^?1 year^?1 during the last 4 years. The soil organic carbon (SOC) significantly increased under all treatments. The estimated annual SOC decomposition rate was 0.35 Mg ha^?1 year^?1 and the equilibrium SOC level was 6.22 Mg ha^?1. Soil total nitrogen (N), available N, total phosphorus (P) and available P under the NPKM treatments increased by 0.15–0.26, 15–33, 0.17–0.66 and 45–159 g kg^?1, respectively, compared with the NPK treatment. Manure application mainly influenced crop yield by affecting the soil TN, available N, and available P, which accounted for up to 64% of the crop yield variation. Taken together, applying manure can determine or at least improve the effects of soil fertility on crop yield in acidic soils in South China.     

Long term effects of fertilization on carbon and nitrogen sequestration and aggregate associated carbon and nitrogen in the Indian sub-Himalayas

An understanding of the dynamics of soil organic carbon (SOC) as affected by farming practices is imperative for maintaining soil productivity and also for restraining global warming by CO₂ evolution. Results of a long-term (30 year) experiment in the Indian Himalayas under rainfed soybean (Glycine max L.)—wheat (Triticum aestivum L.) rotation was analyzed to determine the influence of mineral fertilizer and farmyard manure (FYM) application at 10 Mg ha⁻¹ on SOC and total soil nitrogen (TSN) stocks and distribution within different aggregate size fractions. Fertilizers (NP, NK and NPK) and FYM in combination with N or NPK were applied before the soybean crop every year and no nutrient was applied before the wheat crop. Results showed that addition of FYM with N or NPK fertilizers increased SOC and TSN contents. The overall gain in SOC in the 0- to 45-cm soil depth interval in the plots under NPK + FYM treatment over NPK was 17.18 Mg C ha⁻¹ in 30 year. The rate of conversion of input C to SOC was about 19% of each additional Mg C input per hectare. SOC content in large size aggregates was greater than in smaller size aggregates, and declined with decreased aggregate size. Thus, long-term soybean–wheat rotation in a sandy loam soil of the Indian Himalayas sequestered carbon and nitrogen. Soil organic C and TSN sequestration in the 0.25- to 0.1-mm size fraction is an ideal indicator of long-term C and N sequestration, since this fraction retained maximum SOC/TSN stock.     

Effects of 15 years of manure and inorganic fertilizers on soil organic carbon fractions in a wheat-maize system in the North China Plain

Soil organic carbon (SOC) and its labile fractions are strong determinants of chemical, physical, and biological properties, and soil quality. Thus, a 15-year experiment was established to assess how diverse soil fertility management treatments for winter wheat (Triticum aestivum L.) and summer maize (Zea mays L.) cropping system affect SOC and total N (TN) concentrations in the North China Plain. The field experiment included three treatments: (1) unfertilized control (CK); (2) inorganic fertilizers (INF); and (3) farmyard manure (FYM). Concentrations of SOC, TN, and different labile SOC fractions were evaluated to 1-m depth. In comparison with INF and CK, FYM significantly increased SOC and TN concentrations in the 0–30 cm depth, and also those of dissolved organic C (DOC), microbial biomass C (MBC), hot-water extractable C (HWC), permanganate oxidizable C (KMnO₄–C), and particulate organic C (POC) in the 0–20 cm depth. Despite the higher crop yields over CK, application of INF neither increased the SOC nor the labile C fractions, suggesting that by itself INF is not a significant factor affecting SOC sequestration. Yet, POC (18.0–45.8% of SOC) and HWC (2.0–2.8%) were the most sensitive fractions affected by applications of FYM. Significantly positive correlations were observed between SOC and labile organic C fractions in the 0–20 cm depth. The data support the conclusion that, wherever feasible and practical, application of FYM is important to soil C sequestration and improving soil quality under a wheat/maize system in the North China Plain.     

Organic carbon fractions affected by long-term fertilization in a subtropical paddy soil

Increasing evidence is showing a greater potential for carbon (C) sequestration in paddy soils than in upland soils. However, the mechanisms underlying long-term accumulation and protection of soil organic carbon (SOC) in paddy fields have not been well documented. In the present study, five soil C fractions were separated by physical fractionation in a subtropical paddy field following 27-year differential fertilization regimes (started in 1981). Results showed that, compared to the initial level, long-term rice (Oryza sativa L.) cropping increased SOC concentrations by 28.8, 30.1, 30.8, and 61.6% in the non-fertilized (CK), nitrogen (N), nitrogen-phosphorus-potassium (NPK), and NPK combined with farmyard manure (NPK + FYM) treatments, respectively. Application of FYM enhanced the formation of macroaggregates (>2,000 and 250–2,000 μm), whereas no significant differences in aggregate-size distribution were found among the CK, N, and NPK treatments. Inorganic fertilization (N and NPK) did not affect the concentration of either total SOC or any C fraction as compared with the CK, whereas application of FYM significantly increased the concentrations both in total SOC (25.5%) and in all C fractions, except coarse particulate organic matter (cPOM). Carbon in the paddy soil was dominated by free silt and clay (s + c_f) and intra-aggregate particulate organic matter within microaggregates (iPOM_m) in all treatments that accounted for 46.4–49.6% and 25.1–27.2% of the total SOC, respectively. Furthermore, the differences in C in the iPOM_m and s + c_f fractions between the CK and NPK + FYM treatments accounted for 53.2 and 38.8% of the differences in total SOC stocks, respectively. These results indicate that SOC originating from manure is stored mainly in fractions with slow turnover (i.e., iPOM_m and s + c_f), which may benefit the long-term C sequestration in paddy soils.     

Soil organic carbon contents as a result of various organic amendments to a vertisol

The present study estimates the contributions of various organic amendments to soil organic carbon (SOC). The present work discusses data from a 32-year fertilization experiment using vertisol soil. Five treatments with four field replications were included: no fertilizer (CK), mineral fertilizers only (NPK), wheat straw plus NPK (SNPK), swine manure plus NPK (PMNPK), and cattle manure plus NPK (CMNPK). The ¹³C signature of SOC was measured by δ ¹³C natural isotope technology, and the carbon functional compositions of organic amendments were determined by solid-state ¹³C nuclear magnetic resonance spectra. The average proportions of native and crop residues derived organic carbon under the SNPK, PMNPK and CMNPK treatments were 43, 40, 29, and 51, 51, 39%, respectively. The average proportions of organic carbon-derived from wheat straw (SNPK), swine and cattle manure (PMNPK and CMNPK) were 6, 9, and 32%, respectively. The quantitative relationship between carbon retention efficiency and fertilization year could be described by a significantly negative linear function (p < 0.05). The average organic carbon retention efficiencies for wheat straw, swine, and cattle manure differed substantially at 6, 10, and 31%, respectively. Their corresponding aromatic carbon contents were 6, 7, and 12%, respectively. Furthermore, incorporation of organic amendments, especially for cattle manure, led to a decrease in the yield variability and an increase in the sustainable yield index of crops compared with the CK and NPK treatments. In conclusion, the long-term continuous application of cattle manure is a preferred method for enhancing SOC storage and increasing crop production for vertisols.     

Soil organic carbon fractions after 16-years of applications of fertilizers and organic manure in a Typic Rhodalfs in semi-arid tropics

Agricultural soils can act as a potential sink of the increased carbon dioxide in the atmosphere if managed properly by application of organic manures and balanced fertilizers. However, the rate of carbon (C) sequestration in soils is low in warm climates and thus the short term changes in soil organic carbon (SOC) contents are almost negligible. Therefore, the knowledge about other C fractions that are more sensitive or responsive and indicative of the early changes in SOC can help to determine the effect of the management practices on soil C sequestration. The objective of this study was to determine the soil C sequestration after 16-years of applications of chemical fertilizers and farmyard manure (FYM) to rice (Oryza sativa)—cowpea (Vigna unguiculata) rotation system in a sandy loam soil (Typic Rhodalfs). The treatments were—(1) one control (no fertilizer or FYM); (2) three chemical fertilizer treatments [100 kg N ha⁻¹ (N), 100 kg N ha⁻¹ + 50 kg P₂O₅ ha⁻¹ (NP), 100 kg N ha⁻¹ + 50 kg P₂O₅ ha⁻¹ + 50 kg K₂O ha⁻¹ (NPK)]; (3) one integrated treatment [(50 kg N ha⁻¹ + 25 kg P₂O₅ ha⁻¹ + 25 K₂O ha⁻¹) + (50 kg N ha⁻¹ from FYM)]; and (4) one organic treatment at10 Mg ha⁻¹ FYM. Compared to the control treatment, the increase in SOC was 36, 33, and 19% greater in organic, integrated, and NPK treatments. The 16-years application of fertilizers and/or FYM resulted in much greater changes in water soluble C (WSC), microbial biomass C (MBC), light fraction of C (LFC), and particulate organic matter (POM) than SOC. Of the SOC, the proportion of POM was highest (24–35%), which was followed by LFC (12–14%), MBC (4.6–6.6%), and WSC (0.6–0.8%). The application of fertilizers and/or FYM increased the mean weight diameter of soil aggregates; thus provided physical protection to SOC from decomposition. Our results suggests that the application of fertilizers and/or FYM helps to sequester C in the soil and that the labile fractions of C can be used as indicators to determine the amount of C sequestered as a result of different management practices.     

Soil organic matter dynamics as affected by long-term use of organic and inorganic fertilizers under maize–wheat cropping system

Understanding the effects of long-term use of fertilizers on soil carbon and nitrogen pools and their activities is essential for sustaining soil productivity. Our objectives were to quantify long-term changes in soil organic carbon (SOC), soil microbial biomass carbon (SMBC), soil microbial biomass nitrogen (SMBN) and mineralizable C in maize–wheat cropping sequence in fertilized and unfertilized plots (control, N, NP, NPK, and NPK + FYM). Continuous application of fertilizers increased SOC over its initial content. Active fractions of SOC, i.e., water-soluble carbon, hydrolysable carbohydrates, SMBC, SMBN and dehydrogenase activity, improved significantly with an application of NPK and NPK + FYM. A general increase in carbon mineralization with time period was observed throughout the experiment and was maximum in 100% NPK + FYM treated plots. The estimated annual C input value in NPK + FYM treatment was 1.05 MgC ha⁻¹ year⁻¹. The overall net change in organic carbon was maximum in treatment receiving FYM along with inorganic fertilizers. Therefore, these results suggest that the integrated use of NPK and FYM is an important nutrient management option for sustaining maize–wheat cropping system.     

Effect of long-term application of organic amendment on C storage in relation to global warming potential and biological activities in tropical flooded soil planted to rice

The impact of long term organic amendments on the functional microbial activities, soil carbon (C) storage in relation to greenhouse gas (GHG) emission from rice field was investigated in a tropical Aeric Endoaquept. The treatments included unamended control, farmyard manure (FYM), green manure (GM) (Sesbania aculeata), FYM?+?GM and rice straw (RS)?+?GM combination. Our results suggest that the FYM?+?GM treatment has increased the global warming potential (GWP) by 110?% as well decreased the C efficiency ratio by 24?% in comparison to control. On the other hand, under RS?+?GM treatment the soil organic C and total C contents were significantly higher to the tune of 34 and 53?%, respectively. Our studies clearly reveal that the application of RS?+?GM at 1:1 [Nitrogen (N) basis] could probably be the best soil amendment to sequester the soil organic C. Such amendments may not only have practical application value but also lead to higher yield capacity and minimize emission of GHG under flooded tropical rice soil systems.     

Crop response to manure and fertilizer in Burkina Faso and Niger

Farmyard manure (FYM) is valuable for soil management, especially for soils with <?10 g kg^?1 organic C in semi-arid West Africa. This study determined short-term FYM effects on yield and on response to N, P and K fertilizer for 20 trials in Niger and 28 trials in Burkina Faso involving six crops. The comparisons were of 0 and 2.5 Mg ha^?1 yr^?1 FYM applied in Niger, and of 0 and 5 Mg ha^?1 FYM applied once in 2 years in Burkina Faso. Fertilizer and FYM application alone had little effect on yield in Niger but there was a synergistic effect of fertilizer P with FYM which included increased mean responses to P of, respectively: 0.22 and 0.43 Mg ha^?1 for sorghum grain and fodder (Sorghum bicolor L.); 0.15 and 0.27 Mg ha^?1 for cowpea grain and fodder; 0.16 Mg ha^?1 grain for pearl millet (Pennisetum glaucum L.) when intercropped with cowpea (Vigna unguiculata L.); and 0.39 Mg ha^?1 for groundnut fodder (Arachis hypogea L.). Application of FYM increased pearl millet response to N but decreased legume response to K fertilizer. In Burkina Faso, there was a mean grain yield increase of 0.29 Mg ha^?1 yr^?1 due to FYM and the effect of applying both FYM and fertilizer was additive except for a synergy of N fertilizer plus manure application for maize (Zea mays L.). Therefore, farmers should apply FYM and fertilizer together in Niger but these can be applied alone or together in Burkina Faso with mostly similar effects.     

Studies on the substitution of inorganic fertilizers with organic manure and their effect on soil fertility in rice—wheat rotation

Field studies on the substitution of N and P fertilizers with farm yard manure (FYM) and their effect on the fertility status of a loamy sand soil in rice—wheat rotation are reported. The treatments consisted of application of 12 t FYM ha^–1 in combination with graded levels of N and P. Application of fertilizer N, FYM and their different combinations increased the rice yield significantly. There was no significant response to P application. The magnitude of response to the application of 12 t FYM and its combined use with each of 40 kg and 80 kg N ha^–1 was 0.7, 2.2 and 3.9 t ha^–1 respectively. Application of 120 kg N ha^–1 alone increased the yield by 3.9 t ha^–1, and was comparable to rice yield obtained with 80 kg N and 12 t FYM ha^–1. This indicated that 12 t FYM ha^–1 could be substituted for 40 kg N as inorganic fertilizer in rice. In addition FYM gave residual effects equivalent to 30 kg N and 13.1 kg P ha^–1 in the succeeding wheat. The effect of single or combined use of inorganic fertilizers and FYM was significantly reflected in the build up of available N, P, K and organic carbon contents of the soil. The relationship for predicting rice yield and nutrients uptake were also computed and are discussed.     

Application of liquid cattle manure and inorganic fertilizers affect dry matter,nitrogen accumulation,and partitioning in maize

Efficient use of N applied in the form of organic and inorganic fertilizers is important in maize (Zea mays L.) production to maximize producer’s economic returns and maintain soil and water quality. A field study was conducted for three consecutive years (2003–2005) in Thessaloniki, Greece to investigate whether liquid cattle manure can be used to replace inorganic fertilizers and also whether inorganic fertilizer can be applied preplant or as a combination of preplant and sidedress and can affect maize growth, development and N use efficiency. The treatments were control (unfertilized), liquid dairy cattle manure (Manure), application of 260 kg N ha⁻¹ year⁻¹ as basal dressing (N-single), application of 130 kg ha⁻¹ year⁻¹ N as basal dressing before sowing and 130 kg N ha⁻¹ when plants were at the eight-leaf stage (V8) (N-split). In 2 out of the 3 years of the study there was a significant positive effect of fertilizer application on maize growth, development, N uptake, and partitioning compared with the control. Dry matter production was increased by an average of 39% during the 2 years in plots fertilized either with manure or inorganic fertilizers than the control plots. Also from the yield components kernel weight per ear and number of kernels per ear were increased by an average of 35% and 32%, respectively in the fertilized plots compared with the control plots. Chlorophyll level was affected as it was increased by an average of 18%, 14%, and 18% at the ten-leaf stage (V10), silking and milk stage, respectively in the fertilization treatments compared with the control. Similar trend was observed in the other parameters that were studied. No differences were found between the manure and the different times of N application which indicates that manure can be used to replace inorganic fertilizer. Applying N either preplant in a single application or in split application (half of N preplant and half as sidedress) did not have any effect on any characteristics that were studied indicating that preplant application can be used as it is more cost effective. The present study indicates that liquid cattle manure can be used to replace inorganic fertilizers and also that there was no difference between preplant and sidedress application of N.     

Dissolved organic nitrogen fluxes and crop yield after long-term crop straw incorporation

The transportation of dissolved organic nitrogen (DON) from croplands to aquatic ecosystems potentially negatively influences water quality. Sustaining crop yields while decreasing the environmental impacts of the DON from nitrogen fertilizer application is a key challenge in sustainable agriculture. However, few field datasets have measured the lateral transportation of DON via hydrological routes under different nitrogen fertilizer applications, particularly in sloping croplands. Using lysimeter plots (8?×?4 m²), we measured DON loss via overland flow, interflow, and soil erosion under different fertilizer applications under a long-term field experiment. There were four treatments, including no fertilizer (CK), mineral fertilizer (NPK), mineral fertilizer combined with swine manure (MNPK), and mineral fertilizer combined with crop straw (CNPK). In comparison to the NPK treatment, the annual DON loss fluxes via overland flow, interflow, and soil erosion for the MNPK treatment were significantly (P?<?0.05) increased by 68.8, 100.6, and 63.7%, respectively. Conversely, this was significantly decreased by 182.6, ??14.1, and 49.4%, respectively, under the CNPK treatment. Correspondingly, the yield-scaled total DON losses for the MNPK and CNPK treatments were significantly increased by 78.8 and ??18.2% compared to the NPK treatment (0.33?±?0.04 kg N t^?1 grain). Therefore, long-term continuous manure application is associated with an increased risk of DON environmental pollution. Alternatively, the incorporation of crop straw can be recommended as a means of decreasing DON pollution while maintaining crop yield.     

Pathways of dissolved unreactive phosphorus loss under long-term crop straw and manure application

Dissolved unreactive phosphorus (DUP) loss can increase the risk of water organic and inorganic compound pollution. Because DUP loss under different fertilizers has not been evaluated, selecting a fertilizer that decreases losses but maintains yields remains challenging. Therefore, we compared DUP losses via overland flow, leaching, and sediment in lysimeter plots (8 m?×?4 m?×?0.6 m) with mineral and organic fertilizers for two years. The six treatments, with three replicates, included no fertilizer (CK), mineral fertilizer (NPK), pig manure only (OM), pig manure combined with NPK (OMNPK), crop straw only (RSD), and crop straw combined with NPK (RSDNPK). The results showed that leaching accounted for 54–89% and was the major route for DUP loss. Compared with NPK (0.074 kg ha^?1 year^?1), in the OM and OMNPK, the annual DUP losses via leaching were substantially increased by 11.1% and 8.6%, respectively, whereas they were decreased by 13.2% and 6.2% in the RSD and RSDNPK treatments, respectively. There was a significant positive linear relationship between the soil P surplus and the annual total DUP loss loading (r?=?0.80, p?=?0.05). Compared with the NPK (43.44 kg ha^?1 year^?1), the values of the soil P surplus under the RSD and RSDNPK treatments were greatly reduced by 122.6% and 14.5%, thereby decreasing the annual total DUP loss by 34.5% and 26.4%, respectively. In conclusion, pig manure application can increase DUP leaching risk, whereas the combination of mineral fertilizers and crop straw residues can decrease the DUP loss without compromising the crop yield.