Recycling Of Crop Residues Research Articles

Enchytraeids simultaneously stimulate rice straw degradation and mitigate CO2 release in a paddy soil

The contribution of soil enchytraeids (potworms) to carbon cycling is often considered marginal and is therefore rarely quantified. In our experiment we aimed at evaluating the impact of the model enchytraeid species Enchytraeus buchholzi Vejdovsky, 1879 on rice straw degradation and associated CO2 release from soil. We filled 48 microcosms with soil collected in rice paddies of the Republic of Kalmykia, Russia, at 75% water holding capacity and added 0.5 g dry rice straw sealed in litterbags to each of them. Half of the microcosms were inoculated with 100 potworms. On days 3, 6, 9, 14, 21 and 31 after the start of the experiment, we measured CO2 emissions from soil. In addition, we terminated four microcosms with and four without enchytraeids at each of these dates to measure both rice straw mass loss and enchytraeid recovery rates. E. buchholzi significantly accelerated the relative rice straw mass loss (10.2 ± 1.4 and 14.2 ± 2.0%, respectively). It also significantly reduced CO2 emissions by 35% on average across the whole observation period. Though the number of potworms extracted dropped by 61% of the initial density up to day 9, it then consistently increased and reached a mean density of 365 individuals per microcosm at the end of the experiment. Considering both the rapid reproduction of E. buchholzi and the efficient mitigation of CO2 release, the promotion of enchytraeid activity may be a promising management measure for stabilizing carbon in paddy soils amended with rice straw. This opens up innovative perspectives for further research on exploiting the potential of the soil fauna for sustainable recycling of rice crop residues.

Optimization of nitrogen nutrition of cauliflower intercropped with clover and in rotation with lettuce

Cauliflower (Brassica oleracea var. botrytis L.) requires large amounts of nitrogen (N) fertilizer to produce high yields. The intercropping of cauliflower with a leguminous species may help farmers to reduce N fertilizer rates, production costs and environmental pollution. Moreover, the recycling of crop residues can contribute to the nutritional support of subsequent crops in a rotation. In this study, cauliflower was cultivated in year one either alone or intercropped with annual clover (Trifolium resupinatum L.), using four N fertilization rates: 0, 75, 150, and 300 kg N ha−1 (referred to as N0, N1, N2, and N3 respectively). Following crop residue incorporation in year two, iceberg lettuce (Lactuca sativa var. capitata (L.) Janchen) was cropped on the same field without the supply of N fertilizer to assess the effect of cauliflower and clover residues as well as of residual N fertilizer rates on the growth and N uptake of lettuce.The presence of clover did not affect the marketable yields of the intercropped cauliflower, which were similar to the cauliflower sole-cropped. The N1 and N2 fertilizer rates maximized both growth and N uptake of the intercropped cauliflower, while with the N3, crop development was limited. In the N0 plot, the legume competed for N and depressed growth and N absorption of cauliflower. The sole-cropped cauliflower was, on the contrary, unaffected by the N fertilizer rates. The iceberg lettuce cultivated in succession benefited from the presence of clover in plots N1 and N2. When succeeded to the sole-cropped cauliflower, however, the iceberg lettuce produced less biomass and absorbed less N. Results from this study suggest that the intercropping system cauliflower-clover can be a sustainable tool to optimize N input and reduce N fertilizer requirements for the successive crop.

Bio-intensive Modulation of Sugarcane Ratoon Rhizosphere for Enhanced Soil Health and Sugarcane Productivity Under Tropical Indian Condition

Intensive cropping and exhaustive nature sugarcane crop in tropical India have led to depletion of inherent soil fertility resulting in serious threat to sustainable sugarcane production. Improving soil organic matter and soil fertility are important factors for sustainable sugarcane production. Microbial consortia comprising of Trichoderma viride, Humicola spp, Paecilomyces lilacinus, Gluconacetobater diazotropicus, Azospiriillum brasilense, and Bacillus subtilis have great potential to recycle crop residue and restore soil fertility which eventually promote sugarcane growth. Field experiments with in situ trash management in plant crop and bio-intensive modulation of sugarcane ratoon rhizosphere in ratoon crops were conducted during 2014, 2015 and 2016 at ICAR—Sugarcane Breeding Institute, Coimbatore, Tamil Nadu, India. The results revealed that green manuring with sunnhemp, in situ trash management and application of 280:62.5:120 kg NPK ha−1 in plant crop sustained the soil health by way of reducing soil bulk density (1.26 kg dm−3), lower soil penetration resistance in the ratoon rhizosphere (1.79, 1.82 and 1.75 MPa) and higher soil organic carbon (0.52%) which in turn increased ratoon cane yield 12.24% (99.02 t ha−1) and sugar yield by 8.64% (12.83 t ha−1) over the control. Further, bio-intensive modulation of ratoon rhizosphere by off barring, trash shredding plus soil incorporation with microbial consortia and application of 350:62.5:120 kg NPK ha−1 in ratoon crop recorded significantly higher cane yield (100.95 t ha−1) and sugar yield (13.19 t ha−1) over the control. The improvement in cane yield and sugar yield to the tune of 16.35 and 14.10% due to bio-intensive modulation of ratoon rhizosphere over control have clearly established that productivity of sugarcane ratoon can be significantly improved with balanced use of fertilizers, green manuring, crop residue recycling and microbial consortia application. Similarly, bio-intensive modulation of sugarcane ratoon rhizosphere (S3) with lowest soil bulk density (1.26 kg dm−3) and soil penetration resistance values (1.69, 1.81, and 1.75 MPa) was found effective in minimising the soil compaction and improving nutrient availability (NPK) with build-up of soil microbial population than control (Trash removal). Based on the results of 3-year field experiments, it is concluded that sunnhemp green manuring and in situ sugarcane trash management coupled with application of 280:62.5:120 kg NPK ha−1 in plant crop followed by bio-intensive modulation of ratoon rhizosphere including off barring, trash shredding and soil incorporation with microbial consortia and application of 350:62.5:120 kg NPK ha−1 in ratoon crop can be recommended for sustaining soil health and sugarcane productivity under wide-row sugarcane planting systems of tropical Indian condition.

Soil quality of an Iranian forest ecosystem after conversion to various types of land use.

The impact of land-use change on parameters of the soil was evaluated in soil samples from arable land, orchard land, and grassland in West Azerbaijan, Iran, compared with their adjacent natural forestland, using some biological indices. Microbial biomass carbon (MBC); microbial basal respiration (BR); metabolic quotient (qCO2); substrate induced respiration (SIR); carbon availability index (CAI); the microbial quotient, i.e., the ratio of microbial carbon to soil organic carbon (Cmic/Corg); and soil organic carbon (SOC) were calculated in collected soil samples. Deforestation and long-term land use showed adverse effects on soil biological properties. The spatial distribution of MBC, BR, SIR, and SOC, followed the order: forestland > grassland > orchard land > arable land. SOC showed the highest decline by 67.7% in arable land, 43.6% in orchard land, and 36.3% in grassland, with an average reduction of 49.2% compared with forestland. Similarly, BR and MBC decreased by an average reduction of 41.3 and 34.8%, respectively, compared with forestland. By contrast, the qCO2 index, the CAI index, and the Cmic/Corg ratio were not affected significantly by land use, except from a significant raise of the Cmic/Corg ratio in the arable land. Land-use change exerted a remarkable negative influence on soil quality with several soil attributes affected due to cropping compared with adjacent grassland and forestland. At the field level, proper management practices that increase SOC in the soil, e.g., effective recycling of crop residues and manures, should be considered, when land is continuously cultivated.

Nutrient Decomposition Rate and Sugarcane Yield as Influenced by Mung Bean Intercropping and Crop Residue Recycling

Intercropping and crop residue recycling are intensively applied to enhance the utilization of resources in agricultural systems. To determine the effects of sugarcane and a newly bred mung bean variety intercropping and mung bean crop residue recycling on sugarcane growth and soil, a two-year field study was conducted in Guangxi, China, from 2015 to 2016. The results showed that the sugarcane and mung bean intercropping and mung bean crop residue recycling could improve the growth and the production of sugarcane and enhance the accumulation of dry matter, N, P, and K in the aboveground part of sugarcane as well as the availability of N, P, K, and organic matter in soil. Even though intercropping and crop residue recycling could stimulate the availability of N, P, K, and organic matter, it could not override the negative influence of N, P, and K reductions, but the impact of K reduction was least. Ultimately, the dry matter, N, P, and K of mung bean crop residue on soil surface degraded faster than those of deep burial. Our research suggested that the newly bred mung bean variety is a proper intercropping candidate for sugarcane field in Guangxi.

Nitrogen, Phosphorus, and Antioxidant Contents in Crop Residues for Potential Cascade Utilization

Crop residues are produced intensively in some places, such as plant factories. These residues have further potential as a source of bioactive compounds. Cascade-approach valorization, an approach to recovering bioactive compounds, energy, and fertilizer, could be used for crop residue recycling. In this study, nitrogen, mineral, and bioactive compound contents in crop residues (tomato, watermelon, broccoli, and others) were investigated. The crop residues contained higher mineral amounts than corresponding edible portions in published data, indicating that they could be utilized as an alternative fertilizer. The nitrogen content also tended to be high, and the nitrogen-to-carbon ratio was around ten for the tomato residue. Dilution of nitrogen might be required before bioconversion process such as methane fermentation. Phenolic concentrations were similar for the crop residue and the edible portion, but carotenoids were more concentrated in the residues, especially for the tomato and broccoli cases. High concentrations of quercetin in the tomato residue and chlorogenic acids in the watermelon residue were also measured. Large amounts of crop residues could therefore be a source of bioactive compounds. Because of the negative effects antioxidants have on microbial activity, extracting bioactive compounds prior to the bioconversion process might be advisable.

Effect of in-situ recycling of sugarcane crop residues and its industrial wastes on different soil carbon pools under soybean (Glycine max) - maize (Zea mays) system

A field experiment was conducted during summer 2011-12 at MPKV Farm, Rahuri to evaluate the effect of in-situ recycling of sugarcane crop residues and its industrial wastes on soil organic C fractions like labile carbon, microbial biomass C, particulate organic C, KMnO4 extractable C, physically protected particulate organic matter carbon (POMC) and significantly improved water stable aggregates in the cultivated soil under maize (Zea mays L.)-soybean [Glycine max (L.) Merr.] system. The active carbon pools like soil microbial biomass carbon (SMBC), water soluble carbohydrates (WHC) and acid hydrolysable carbon (AHC) was significantly improved in the treatment receiving 100% recommended dose of fertilizer along with in-situ compost of crop residues, press mud cake and methanated spent wash compost compared to burning of residues. Application of in-situ sugarcane residues with pressmud incorporation retainedabout19.6%, 38.8% and 33% more amount of total organic carbon (TOC), SMBC, AHC respectively, over burning of sugarcane crop residues and removal of stubbles after harvest of maize. The mean values of WSC (43 mg/kg) and the physically protected carbon, i.e. POMC (2014 mg/kg) were greater by 47% and 6.6% respectively, in the treatment (T7) receiving in-situ residue decomposition of sugarcane crop residues in combination with equal proportion (50%) of press mud cake and biomethanated spent wash over the burning of sugarcane crop residues and removal of stubbles after harvest of maize. After harvest of maize the maximum recalcitrant fraction (humic acid) of carbon was observed in the treatment T7 (in-situ decomposition of sugarcane crop residues + 50% press-mud cake + 50% biomethenated spent wash). This study clearly indicated that resistant fraction of carbon might be accumulated more where decomposed organic matter was applied regularly. It clearly indicated that application of in-situ decomposed residues and by-products of industrial waste in combination with NPK enhanced the below and above ground biomass production, SOC stock and carbon pools.

Crop residue quality and soil type influence the priming effect but not the fate of crop residue C

Crop residues and soil types play an important role in soil C and N storage. The objectives of this study were to quantify the effects of crop residue quality and interactions with soil type on soil C and N, in the short- and medium-term, and to determine the responses related to the priming effect (PE). Residues of vetch (Vicia sativa L.), pea (Pisum sativum L.) and wheat (Triticum aestivum L.) crops with different chemical compositions and labelled with 13C and 15N were left to decompose on the surface of either a sandy-loam soil or a clay soil incubated under laboratory conditions at 25 °C for 360 days. We measured the total CO2-C and CO2-13C emitted during decomposition, the soil mineral N content and the amounts of 13C and 15N remaining in both the surface residue particles and the bulk soil. Over the short-term, the vetch residues decomposed faster than those of wheat and pea on the soil surface due to their more favourable chemical composition for biodegradation; after one year, however, this difference disappeared. We observed extra soil C mineralization in all cases, i.e., the PE was positive for all treatments and was directly related to the water-soluble (vetch > pea > wheat) and soil C contents (clay soil > sandy-loam soil). Conversely, the fate of the added 15N and net N mineralization differed considerably between the three residues and was strongly related to the initial N content of the residue. Crop residue quality and soil type affected the soil PE and soil C balance but not the fate of crop residue-C after one year. Net soil N mineralization was observed in all crop residues, with large early differences (vetch > pea > wheat), which were maintained on a medium-term basis. Our results emphasize the need to jointly consider C and N dynamics as well as short- and medium-term effects to manage agricultural and environmental services provided by the recycling of crop residues to agricultural soils.

Economics analysis on yield of cotton as influenced by sulphur and micronutrients

Cotton is still the principal commercial crop touching the country’s economy at several points. It is also an important commercial crop of Karnataka and cultivated on an area of 4.78 lakh ha with a production of 6.77 lakh bales (Anonymous, 2003). With the introduction of high yielding and fertilizer responsive varieties, the practices of using large amounts of high analysis macronutrient fertilizers with much decreased use of organic manures and little recycling of crop residues led to micronutrient hunger in many crops. Generally the need of the micronutrients has been essentially and entirely met through its native reserve in the soil (Singh, 1999), Inspite of liberal application of N, P and K fertilizers, normal growth of high yielding varieties of crop could not be achieved due to little appreciation of the use of secondary and micronutrients. High fertilizer responsive varieties can express their full yield potential only when limiting trace elements fertilizers are also applied along with NPK fertilizers. Since, information on economic aspects of production of cotton (RAHB-87) is lacking in northern transitional zone (Zone-8) of Karnataka, the present study was carried out to know the optimum dose of nutrients, required to produce maximum yield which economically viable. A field experiment was conducted on medium black soil having initial organic carbon content of 0.58 per cent, pH 7.30, available nitrogen phosphorus and potassium content of soil were 315, 22.0, 390 kg/ha, respectively. The experiment was laid out in randomized block design in 3 replications with nine treatment combinations. Results revealed that treatment (T 9 ) receiving combined application of sulphur, iron, zinc each at 50 kg per ha recoded highest seed cotton yield (25.12 q/ha) which was on par with treatment (T 8 ) receiving combined application of sulphur, iron and zinc each at 25 kg per ha. These two treatments were significantly superior over control. Economic analysis of the system revealed that, Economics analysis on yield of cotton as influenced by sulphur and micronutrients

Assessing village-level carbon balance due to greenhouse gas mitigation interventions using EX-ACT model

Under National Initiative on Climate Resilient Agriculture (NICRA) project, a range of climate smart agricultural practices were evaluated with on-farm demonstrations during 2011–2013 in eight climatically vulnerable villages of Andhra Pradesh, India. Proven climate smart practices viz residue recycling, soil, water and nutrient management, afforestation and feeding + breeding practices in livestock were implemented in annual and perennial crops, irrigated rice, horticulture, fodder, forestry and livestock. An EX-ante carbon-balance tool (EX-ACT) developed by the FAO was used with a combination of various climate smart interventions to know the mitigation potentials in eight climatically vulnerable villages of Andhra Pradesh, India. Based on our observations, EX-ACT model had shown that these practices were effective to mitigate CO2 emissions apart from enhancing soil productivity. In Nacharam, Yagantipalli, Sirusuwada and Matsyapuri villages, climate smart practices implemented in annual crops along with crop residue recycling, crop and water management practices resulted in negative carbon (C) balance by −16,410, −8851, −7271 and −6125 t CO2 e, respectively. The EX-ACT model predicted positive carbon balance with irrigated module in the rice-growing villages of Sirusuwada and Matsyapuri villages. The negative values suggest a sink, and positive values a source for CO2 emissions. In Chamaluru village, although there were CO2 emissions (source) due to livestock and non-forest and land use changes, there was a carbon sink due to other activities as predicted by the model. The results suggested that various climatic smart practices at the village level were successful in creating net sink of CO2 emissions (t CO2 e).

Effect of In situ Recycling of Sugarcane Crop Residues on Soil Enzyme Activities Under Soybean–Maize System

An investigation was carried out by conducting a field experiment at the farm of the Mahatma Phule Krishi Vidyapeeth (MPKV), Rahuri. The significant grain yield of soybean (37.5 q ha−1) and maize (49 q ha−1) were observed in the treatment receiving 100 % recommended doses of Nitrogen, Phosphorus and Potassium (NPK) + in situ compost of crop residues, pressmud compost (T6). After harvest of maize dehydrogenase activity, acid phosphatase, β-glucosidase and urease were significantly improved in T7 treatment as compared to other treatments. However, fluorescein diacetate activity and alkaline phosphatase were significantly greater in T6 treatment in post-harvest soil samples of maize. In the post-harvest soil of maize the bacterial and actinomycetes population were greater in the treatment receiving in situ decomposition of sugarcane crop residues + 100 % recommended dose of NPK (T3). The fungal population after harvest of maize was found maximum in treatment T7. The total organic carbon was significantly correlated with dehydrogenase (r = 0.65, P < 0.01), fluorescein diacetate (r = 0.71, P < 0.01), acid phosphatase (r = 0.66, P < 0.01), β-glucosidase (r = 0.65, P < 0.01), and urease (r = 0.57, P < 0.01). There was a significant correlation (r = 0.77, P < 0.01) between TOC and soybean yield, and between total organic carbon and maize yield (r = 0.98, P < 0.01). The result suggest that in situ recycling of sugarcane crop residues and the industrial wastes with suitable interventions like use of bioinoculum, phosphatic fertilizer and urea may help for improving better crop productivity and soil biological activities.

Decomposition and nutrient release pattern of wheat (Triticum aestivum) residues under different treatments in desert field conditions of Sudan

Background Recycling of crop residues is essential to sustain soil fertility and crop production. Therefore, it is of crucial importance to study the decomposition of crop residues particularly in the arid tropics. The decomposition and nutrient release pattern from crop residues incorporated in the soil have rarely been investigated under semiarid climatic conditions in Sudan. Decomposition and nutrient release pattern from wheat residue were investigated in a 12 week litter bag experiment under field condition. Litter bags contain 50 g wheat residue were buried in plots cultivated with guar and treated with following treatments: crop residue (CR), recommended fertilizer ? crop residue (RF ? CR), sewage sludge (SS) and non treated control (C). In each plot of each block, 12 litter bags were buried. Four bags from each treatment were retrieved at 2, 4, 6, 8, 10 and 12 weeks of decomposition. The decomposed residue was analysed for remaining dry matter (DM), nitrogen (N), phosphorus (P), potassium (K) calcium (Ca), and magnesium (Mg) contents. Mass loss and nutrients released from wheat residue followed the exponential model, Wt = W0 9 e -kt from which the specific decay rate constants (k) and t0.5 and t0.95 were

Macronutrient uptake, accumulation and export by the irrigated 'vitória' pineapple plant

The nutritional state of the pineapple plant has a large effect on plant growth, on fruit production, and fruit quality. The aim of this study was to assess the uptake, accumulation, and export of nutrients by the irrigated 'Vitória' pineapple plant during and at the end of its development. A randomized block statistical design with four replications was used. The treatments were defined by different times of plant collection: at 270, 330, 390, 450, 510, 570, 690, 750, and 810 days after planting (DAP). The collected plants were separated into the following components: leaves, stem, roots, fruit, and slips for determination of fresh and dry matter weight at 65 ºC. After drying, the plant components were ground for characterization of the composition and content of nutrients taken up and exported by the pineapple plant. The results were subjected to analysis of variance, and non-linear regression models were fitted for the significant differences identified by the F test (p&lt;0.01). The leaves and the stem were the plant components that showed the greatest accumulation of nutrients. For production of 72 t ha-1 of fruit, the macronutrient accumulation in the 'Vitória' pineapple exhibited the following decreasing order: K &gt; N &gt; S &gt; Ca &gt; Mg &gt; P, which corresponded to 898, 452, 134, 129, 126, and 107 kg ha-1, respectively, of total accumulation. The export of macronutrients by the pineapple fruit was in the following decreasing order: K &gt; N &gt; S &gt; Ca &gt; P &gt; Mg, which was equivalent to 18, 17, 11, 8, 8, and 5 %, respectively, of the total accumulated by the pineapple. The 'Vitória' pineapple plant exported 78 kg ha-1 of N, 8 kg ha-1 of P, 164 kg ha-1 of K, 14 kg ha-1 of S, 10 kg ha-1 of Ca, and 6 kg ha-1 of Mg by the fruit. The nutrient content exported by the fruits represent important components of nutrient extraction from the soil, which need to be restored, while the nutrients contained in the leaves, stems and roots can be incorporated in the soil within a program of recycling of crop residues.

Impact of Innovation on Smallholders’ Productivity and Poverty Status: The Case of Arable Crop Farmers in South-East, Nigeria

Agriculture is the prevalent occupation of most rural households especially in Nigeria. Raising the productivity of these rural households is crucial in reducing rural poverty and hunger. Innovation adoption is key to increasing farm productivity. This necessitated this study on innovation adoption, farm productivity and poverty status of rural smallholder farm households in South-Eastern Nigeria. This was premised on the fact that increasing agricultural productivity through adoption of innovation can increase food availability and access as well as rural incomes. Multistage sampling proceedure was used in selecting the respondents used for this study. Data collected using structured questionnaire and interview schedules were analyzed using descriptive statistical tools such as frequency tables, percentages, regression analysis and Chow’s test statistic. Result of data analysis revealed that the most adopted innovations/technologies were use of iinorganic fertilizer, improved seed, terracing, crop residue recycling, crop rotation and use animal waste. The significant factors influencing adoption of the innovations/technologies were gender, age, years of formal education attainment, household income, extension contact and membership of cooperative. The Chow’s test revealed that innovation/technology

Effects of Biochar Derived from Maize Stover and Rice Straw on the Early Growth of their Seedlings

Crop residues such as maize and rice are important sources of nutrients and their restitution to the soil is an important residue management strategy for maintaining or improving soil and crop productivity. However, most maize and rice farmers in Sierra Leone burn crop residues during land preparation thereby depriving the soil of this vital resource. An alternative approach is the recycling of crop residues through biochar production. This study was therefore carried out to assess the effects of (i) maize stover biochar on the early growth of maize and (ii) rice straw biochar on the early growth of rice. In this study, biochar (0g, 12.5g, 25.0g, 37.5g and 50.0g) was mixed with 3kg of soil (fine sandy loam) and placed in perforated black polythene bags. Maize or rice seeds (3 per pot) were planted to 2cm depth and later thinned to one plant per pot. All pots were placed in the open under direct sunlight and rainfall. No supplemental irrigation was done since there was sufficient rainfall to supply the required moisture. The experiment was laid in completely randomized design with five treatments and three replications. After four weeks, the experiment was terminated. Mean plant height, stem girth, fresh- and dry-shoot weights of both maize and rice plants generally increased significantly (p<0.05) relative to the control at biochar applications ≥8.3g/kg soil. The results showed that growing maize and rice on soils treated with biochar derived from their residues (maize stover and rice straw respectively) has the potential to improve crop production. Confirmatory field trials and costs/benefits analysis of converting rice and maize residues to biochar will serve as a good guide for policy makers and end-users (farmers) for increased productivity of maize and rice in Sierra Leone.

Physical and hydraulic properties of aridisols as affected by nutrient and crop-residue management in a cotton-wheat system

A 5-year cotton-wheat rotation field experiment was conducted on two alkaline-calcareous soils to investigate the impact of integrated nutrient-management and crop-residue incorporation on soil physical and hydrological properties. The nutrient treatments were: T1-farmers' fertilizer use; T2- balanced nutrient management (recommended N, P, Zn. and B from mineral sources); T3-integrated nutrient management, same as T2, except that 75% N was applied from fertilizer and 25% as FYM; and T4 same as T2, except that every alternate year, wheat was substituted by Berseem green manure. All treatments were compared with and without crop residue incorporation. Soil organic matter (SOM) content in both the soils was significantly increased with T2, T3 and T4 as compared with T1, and was increased further where the nutrient-management treatments were applied in combination with crop-residue recycling. Higher increase in SOM content was observed in soil having relatively lower initial SOM (0.61%) than soil having initial 0.80% SOM content. Increased SOM content, in return, decreased soil bulk density, improved macro- and meso-porosity, and enhanced percent recovery of stable aggregates correspondingly. Infiltration rates were 20, 49 and 26% higher with T2, T3 and T4, respectively, over T1 and 64% higher with crop-residue incorporation over crop-residue removal. Positive impacts on soil physical properties were also observed in the sub-soil layers.

Assessing the potential of crop residue recycling in China and technology options based on a bottom-up model

Crop residues are an important biomass, and are significant in the sustainable development of China. This paper uses the Grey-Markov modeling approach, the cost-benefit analysis method, and the constraint optimization method to establish the potential of crop residue recycling in China (CRRC) using a bottom-up analysis. Taking 2010 as the baseline year, the CRRC model is used to determine the quantity trends of crop residue resources, simulating the recycling potential and selecting key crop residue recycling technologies for operation between 2010 and 2030. The results illustrate that the total residue output from different crops will gradually increase to 1062 million tons in 2030. The proportion of crop residue for field burning is expected to decrease as a result of guidance and support from the government. Market mechanisms are also improving the development of the crop residue recycling industry. The economic benefit of crop residue recycling is expected to be worth 132 billion CNY in 2030 according to technology structure options. Key crop residue recycling technologies preferred such as liquefaction, amination, silo, co-firing straw power and composting will account for more than 85% of the total benefits.

NUTRIENT BALANCES AS AFFECTED BY INTEGRATED NUTRIENT AND CROP RESIDUE MANAGEMENT IN COTTON-WHEAT SYSTEM IN ARIDISOLS. I. NITROGEN

A five-year cotton–wheat rotation field experiment was conducted on two alkaline-calcareous soils, i.e., Awagat (coarse loamy) and Shahpur (fine silty), to investigate the impact of integrated nutrient and crop residue management on soil and crop productivity. Apparent nitrogen (N) balances were developed. Minimum five-year mean yield (Mg ha−1), obtained with Farmers’ Fertilizer Use (FFU) treatment was: cotton – Awagat, 2.19; Shahpur, 2.45; wheat – Awagat, 3.03; Shahpur, 3.94. With Balance Nutrient Management (BNM), yields increased (P ≤ 0.05) for cotton, 24% in Awagat and 18% in Shahpur soil; and wheat, 37% in Awagat and 24% in Shahpur soil. Maximum crop yields were obtained with Integrated Nutrient Management (INM), i.e., 3–5% higher than with BNM. Crop residue recycling increased the yields further, cotton by 2−7% and wheat by 2–10%. All nutrient management treatments, except for FFU without crop residue recycling, resulted in positive apparent N balances. INM improved SOM and NO3-N, contents.

NUTRIENT BALANCES AS AFFECTED BY INTEGRATED NUTRIENT AND CROP RESIDUE MANAGEMENT IN COTTON-WHEAT SYSTEM IN ARIDISOLS. III. POTASSIUM

Potassium (K) uptake, uptake trend and apparent balances as influenced by integrated nutrient and crop residue management were investigated in a five-year field experiment on two calcareous soils, i.e., Awagat (coarse loamy) and Shahpur (fine silty) in cotton-wheat sequence. Total K uptake by cotton and wheat plants differed significantly due to nutrient management treatments, i.e., farmers’ fertilizer use (FFU); balanced nutrient management (BNM); integrated nutrient management (INM); and balanced nutrient management plus green manuring (BNM+GM). Minimum mean K uptake (kg ha−1) by cotton with FFU was 87.1 in Awaga and 108.1 in Shahpur. Corresponding maximum mean K uptake with INM was 115.1 and 132.2, respectively. Nutrient treatments effect on K uptake by wheat was similar to cotton. Potassium uptake was further enhanced by crop residue recycling. Potassium uptake by both crops exhibited non-significant trends and large negative apparent K balances were observed in both the soils.

NUTRIENT BALANCES AS AFFECTED BY INTEGRATED NUTRIENT AND CROP RESIDUE MANAGEMENT IN COTTON-WHEAT SYSTEM IN ARIDISOLS. II. PHOSPHORUS

Impact of integrated nutrient and crop residue management on crop productivity, phosphorus (P) uptake and apparent P balances was investigated in a 5-year field experiment on two calcareous soils, i.e., Awagat (coarse loamy) and Shahpur (fine silty) in cotton-wheat sequence. Minimum mean P uptake (kg ha−1) by cotton with Farmers’ Fertilizer Use (FFU) treatment was 8.89 in Awagat and 11.54 in Shahpur soil. Corresponding maximum mean P uptake was 15.30 and 17.01 kg ha−1 with Integrated Nutrient Management (INM), respectively. Nutrient treatments effect on P uptake by wheat was similar to cotton. Phosphorus uptake was further enhanced by crop residue recycling. Phosphorus uptake trend by cotton was negative under FFU without residue recycling and was positive with residue recycling. While P uptake trends were positive under all other treatments. INM yielded positive apparent P balances (kg ha−1) of 56–306 in Awagat and 24–288 in Shahpur soil.