Fertilizer Response Research Articles

Response of Chemical Fertilizers and INM on Productivity of Wheat (Triticum aestivum L.) and Properties of Soil

A field experiment was conducted during rabi season of (2020-21) on wheat at Research Farm of Kulbhaskar Ashram Post Graduate College, Prayagraj (UP), to find out the Response of Chemical Fertilizers and INM on Productivity of Wheat (Triticum aestivum L.), and Properties of Soil. The experiment laid out in Randomized Block Design (RBD) with eleven treatments and three replications. The results revealed that the highest plant height was recorded in treatment T11 (75% RDF +5 t ha1 FYM +20 kg ha1 ZnSO4 +Azotobacter and PSB), which was significantly superior over treatment T3, T4 and T5. The maximum yield attributing characters (number of spikes per m2, spike length, number of grains per spike and test weight), and yield (grain and straw), were increased with treatment receiving 75% RDF +5 t ha1 FYM +20 kg ha1 ZnSO4 +Azotobacter and PSB (T11). The maximum enhancement in grain and straw yield of wheat was recorded in treatment T11 (75% RDF +5 t ha1 FYM +20 kg ha1 ZnSO4 +Azotobacter and PSB), which was significantly superior over T2, T3, T4, T5, T8 and T9. The maximum protein content (13.18%), in grain of wheat was found in treatment T11 (75% RDF +5 t ha-1 FYM +20 kg ha1 ZnSO4 +Azotobacter and PSB), The application of FYM with Chemical Fertilizers and Bio-fertilizers (Azotobacter and PSB) improved in soil pH and EC and also increased the Soil Organic Carbon and Available N, P & K in soil after the harvest of crop. The treatment (T11). was found best in respect of soil properties.

Robusta Coffee Growth Response to Application of Various Liquid Organic Fertilizers in Replacing C-Organic and N-Total Soil

The Ministry of Agriculture through the Agricultural Quarantine Agency (2019) stated that Robusta coffee has contributed 41% of the country's foreign exchange, with an average export frequency of 102 times per month, and will continue to increase. In connection with the growth in export volume of robusta coffee, coffee farmers need additional substances for the soil in the form of nutrients to be able to meet the soil nutrient needs for coffee from planting to harvest. Organic fertilizer in liquid form is one type of fertilizer that can be an option, in addition to facilitating nutrient absorption. This study aims to determine the response of various liquid organic fertilizers at certain concentrations to the vegetative growth of robusta coffee. The content of C-organic and total Nitogen in the soil which has been given the addition of gamal liquid organic fertilizer and tofu wastewater with the addition of citronella can provide a very significant difference in the vegetative growth of robusta coffee plants at the age of 60 HSP at plant height, and 90 HSP in diameter. stem and number of leaves (strands). Based on the results of laboratory tests carried out, it was also known that the macro and micro nutrient content in the soil with the addition of poc of tofu wastewater which was given citronella had a good content compared to the control and soil conditions with the addition of gamal liquid organic fertilizer.

Fertility response following ablation-induced follicular wave emergence and ovulation induction in anestrous buffaloes

The fertility response following induction of follicular wave emergence by follicle ablation combined withprogesterone based ovulation synchronization in postpartum anestrous buffaloes was assessed. Postpartum anestrousbuffaloes (n=24) with absence of overt estrus signs categorized as treatment group (Group 1; n=15) and controlgroup (Group 2; n=9). Group 1 was subjected to transvaginal ultrasound-guided follicle ablation on a random dayof the estrous cycle (Day=0) and insertion of CIDR. Seven days later, CIDR was removed and prostaglandin F2αanalogue was given intramuscularly. GnRH analogue was injected on day 9.5 and fixed-time AI was done 12 h and24 h later. Ultrasonography was performed to follow ovarian structures on different occasions and on day 38 postovulationfor detecting pregnancy. Group 2 did not receive any treatment however, estrus detection in this groupwas done daily by bull parading and visual monitoring followed by AI if found in standing estrus. In treatmentgroup, the follicular wave emergence occurred by 24 h following ablation in 60% buffaloes and in 40% remaininganimals by 48 h. The estrus exhibition was 100 % in group 1 versus 22.2 % in group 2. Mean interval from CIDRremoval to ovulation was 81.2±3.08 h and from wave emergence to ovulation was 9.92±0.18 days. The first servicepregnancy rate in treatment group was higher than control (66.67% vs 22.2%). The induction of follicular waveemergence through ultrasound guided follicle ablation and progesterone based ovulation synchronization can beused to improve pregnancy rates in anestrous buffaloes.

Integrated Nutrient Management Improves the Productivity and Nutrient Use Efficiency of Lens culinaris Medik.

Enhancing nutrient use efficiencies (NUEs) is an important factor in achieving the long-term sustainability of a production system. Our two-year experiment was aimed at accessing the NUEs of the integration of macro- and micronutrient fertilization responses of three lentil (Lens culinaris) cultivars. Three cultivars were planted in the main plots, and ten nutrient combinations were used in the sub-plots: N1, control; N2, 100% recommended dose of fertilizers (RDF) (20:40—N:P2O5); N3, vermicompost (VC) at 2 t ha−1; N4, 50% recommended dose of nitrogen (RDN) + 100% recommended dose of phosphorus (RDP) + VC at 1 t ha−1; N5, RDF + 0.5% ZnSO4; N6, RDF + 0.5% FeSO4; N7, RDF + 0.5% ZnSO4 + 0.5% FeSO4; N8, 50% RDN + 100% RDP + VC at 1 t ha−1 + 0.5% ZnSO4; N9, 50% RDN + 100% RDP + VC at 1 t ha−1 + 0.5% FeSO4; and N10, 50% RDN + 100% RDP + VC at 1 t ha−1 + 0.5% ZnSO4 + 0.5% FeSO4. The results show that the cultivar HM-1 (1.59–1.61 Mg ha−1) recorded a significantly higher seed yield than cultivars Sapna (1.31–1.33 Mg ha−1) and Garima (both 1.30 Mg ha−1), while the cultivar Sapna had significantly more stover yield (1.86–1.90 Mg ha−1) than cultivar HM-1 (1.68–1.73 Mg ha−1). Cultivar HM-1 was more efficient in terms of partial factor productivity for N (77.5–78.5 kg kg−1), P (48.2–48.7 kg kg−1), K (143.6–145.5 kg kg−1), Zn (1336–1352 kg kg−1), and Fe (417–421 kg kg−1) than Sapna and Garima. Application of 50% N + 100% P + VC at 1.0 t ha−1 + 0.5% ZnSO4 + 0.5% FeSO4 resulted in higher seed yield (1.63–1.65 Mg ha−1) and agronomic efficiency for N (26.3–28.8 kg kg−1), P (12.42–13.63 kg kg−1), and K (52.3–57.4 kg kg−1) over other tested practices in both years. Hence, it could be concluded that considering the integrated nutrient management paradigm including 10 kg N ha−1 coupled with 40 kg P2O5 ha−1 through synthetic fertilizers, vermicomposting 1.0 t ha−1 as an organic source and foliar spray of 0.5% each of ZnSO4 and FeSO4 (N10) produced a 56.8% higher seed yield than the control, in addition to improving nutrient dynamics and NUEs for N, P, K, Zn, and Fe. Therefore, integrated fertilization coupled with cultivar selection could help to achieve the long-term food and nutritional sustainability targeted by the Sustainable Development Goals (SDGs).

Estrus and fertility responses in acyclic ewes treated with short, medium or long-term GnRH-PGF2α-GnRH protocols supplemented with intra-vaginal progesterone therapy

The present study was conducted with the aim to compare the effectiveness of the short-term (5 days), moderateterm (8 days) and long-term (12 days) progesterone therapy in the form of intravaginal AVIKESIL-S® progesterone sponge developed by CSWRI, Avikanagar (Rajasthan), during modified GnRH-PGF2α-GnRH treatments during non-breeding season (May-July) in crossbred (Nali×Rambuillet) ewes. The seasonal anestrus ewes were enrolled into four groups. In Group 1 (n=50), ewes were treated with GnRH on day 0, PGF2α on day 5, and second GnRH on day 7 plus progesterone supplementation with intravaginal progesterone sponge from day 0 to day 5 while in Group-2 (n=50), ewes were treated with GnRH on day 0, PGF2α on day 8, and second GnRH on day 9 plusprogesterone supplementation with intravaginal progesterone sponge from day 0 to day 8. Further, in Group 3(n=50), ewes were treated with GnRH on day 0 and PGF2α on day 12 and second GnRH on day 13 plus progesteronesupplementation with intravaginal AVIKESIL-S® sponge from day 0 to day 12. Group 4 (n=50), comprised ofuntreated control animals. Results showed that estrus synchronization rate (%) was significantly higher in Group 2and Group 3 in comparison to Group 4 (control). There was significant difference in the duration of estrus, pregnancy rate, lambing rate in Group 2 as compared to Group 4 (control) but prolificacy and fecundity were not statistically significant (p>0.01) among the groups during out of breeding season. Thus, modified Ovsynch protocol with 8-day progesterone therapy is better for augmenting fertility in crossbred ewes during non-breeding season.

Comparative study of short term and long term protocols for progesterone based estrus synchronization in ewes during breeding season

The study was designed to compare the effect of length of progesterone treatment (6 d vs 10 d vs 14 d) on synchronization efficiency and fertility response in multiparous ewes. The crossbred ewes (30) were equally allotted to three groups designated as short (6 days), medium (10 days) and long-term (14 days) treatment. All the ewes were injected PGF2α 250 μg, intramuscularly 24 h before sponge removal. After the sponge removal ewes were kept with breeding rams for tupping upto 72 h. Although the onset of estrus was more precise in short and long term groups, however overall estrus response rate was highest in short treatment group (90%) followed by long treatment group (70%) and medium treatment group (60%). The pregnancy rates were non-significantly higher for short and medium treatment groups than long treatment group. The progesterone values in pregnant ewes, decreased significantly from day pre-treatment to day 0 followed by significant increase from day 0 to day 10, 17 and 35. In conclusion, short term (6 d) intravaginal progesterone treatment may replace the traditional long term treatment (14 d) for induction of estrous during breeding season. However, the results should be validated in larger number of animals before recommending the protocol.

Sorghum yield response to NPKS and NPZn nutrients along sorghum-growing landscapes

Summary Grain sorghum [Sorghum bicolor (L.) Moench] is the major cereal crop used as staple crop in the arid and semi-arid regions of Ethiopia. Low sorghum yields are attributed to soil, climate and topographic factors. We investigated sorghum yield response to factorial combination of nitrogen and phosphorous (NP) as well as potassium (K), sulphur (S) and zinc (Zn), and how the position of farmers’ fields belonging to different landscape positions (i.e., upslope, mid-slope, and foot slope) could explain fertilizer response and yield variability. The analysis in this study made use of dataset from two sets of on-farm experiments where trials were set at two farmers’ fields for NPKS and three farmers’ fields for NPZn experiments in each landscape position. The experiments were implemented at two sorghum-growing locations (i.e., Hayk and Sirinka) in parts of the north-eastern Amhara region in Ethiopia. Sorghum yield response to fertilizer application was strongly linked to the spatial variation along landscape positions and varied over locations. Fertilizer response was significantly higher at foot slopes compared to mid-slopes and upslope positions, where fields at foot slopes exhibited relatively homogeneous responses. Application of combined nitrogen (N) and phosphorus (P) fertilizers, landscape position and the interaction of fertilizer application and landscape positions strongly affected sorghum yield. There was a linear and significant increase in sorghum yield with the increase in the NP rates. The combined application of NP with different levels of KS as well as NP with Zn fertilizer rates did not result in significant yield difference. The results indicated that local factors were much more influential when accounting for the heterogeneity in sorghum yield response to fertilizer. This further acknowledges the importance of a landscape-based fertilizer management approach to respond yield potential variability related with the farmers’ fields and landscape environment. Further investigation is needed to develop homogeneous fertilizer response units based on spatial variability of soil and topographic attributes along the landscape.

Plantation tree growth responses to P, N, K and minor and trace elements on low fertility savanna soils

Context Widespread soil nutrient limitations in savanna soils typically constrain plantation tree growth, and hence limit economic opportunities in tropical regions. Fertilisation offers an approach to overcome soil nutrient limitations, but requires research on nutrient contents and rates to maximise plant growth while avoiding nutrient imbalances that have stunted plant growth under some fertiliser regimes. Aims To test the hypothesis that multiple nutrient limitations exist in savanna soils, with nutrient deficiencies exposed in sequence with fertiliser addition. Methods Factorial field experiments tested the growth of the plantation timber species African mahogany (Khaya senegalensis) to applications of phosphorus, potassium, nitrogen and minor and trace elements (referred to as the T treatment) on a kandosol soil near Darwin, Australia. Key results Under high stocking rates to induce deficiencies sooner through utilisation of a high proportion of the available nutrient capital, positive responses and interactions to all four main treatments were recorded. There were step-wise responses to phosphorus, potassium, nitrogen and the T treatment. Treatments with greater mean tree growth were more uniform than lesser-growing treatments, even though the largest and smallest individuals were similar across treatments. Conclusions Consistent with our hypothesis, correcting one soil nutrient deficiency exposed another in sequence as nutrient reserves were depleted in a drying soil. Variation in tree performance across plots indicates that testing of soil nutrients and fertiliser responses need to be assessed in replicate and dispersed samples. Implications Khaya senegalensis demonstrated potential for plantation use in northern Australia with minimal mortality from termites and other causes, if supported with broad-spectrum fertilisation balanced to match plant growth and water availability.

Pregnancies and contraceptive use in four African countries during the COVID-19 pandemic

The COVID-19 pandemic and the public health measures adopted in response to it have triggered plenty of speculation about the potential impact on fertility in different regions of the globe. This study provides evidence on the fertility response in four sub-Saharan African countries during the first year of the pandemic. Using harmonized data on women of childbearing age from the Performance Monitoring for Action (PMA) data series, this study compares pregnancy rates at the turn of the year 2020/21 to a pre-pandemic baseline. There is no indication of a general increase in pregnancy rates after the beginning of the pandemic. In some of the sample countries, pregnancy rates during this phase of the COVID-19 pandemic instead fell significantly among the youngest and the least educated women of childbearing age, respectively. The findings also indicate that over this period, rates of modern contraceptive usage rose significantly among the surveyed female populations in several sample countries.

Fertility Response Following Estradoublesynch and Progesterone Based Ovsynch Protocols in Delayed Pubertal Buffalo Heifers

The study evaluated the fertility response following Estradoublesynch and progesterone-based Ovsynch protocols in delayed pubertal buffalo heifers. A total of twenty delayed pubertal buffalo heifers were subdivided in two equal subgroups. Group I animals were treated with PGF2α analogue (500 µg cloprostenol sodium) i.m. on day 0, GnRH analogue (20 µg buserelin acetate) on day 2, PGF2α analogue (500 µg cloprostenol sodium) repeated on day 9 and estradiol benzoate 1 mg intramuscular (i.m.) on day 10. Fixed-time artificial insemination (FTAI) was done at 48 and 60h. Group II animals were subjected to GnRH analogue (20 µg buserelin acetate) i.m. along with CIDR insert intravaginally on day 0, PGF2α analogue (500 µg cloprostenol sodium) i.m. and removal of CIDR on day 7, GnRH analogue on day 9 followed by FTAI at 12 and 24h. Blood collection (plasma P4) and ultrasonography (luteal and follicular dynamics) was performed on day 0, 9, 10, 12 in group I and day 0, 7, 9 and 10 in group II animals. Pregnancy diagnosis was made at 45-60 days post AI. Estrus response was observed in all the buffalo heifers of group I and II. First service conception rate was significantly higher in group I (50%) compared to group II (20%) (P<0.05). Overall pregnancy rate was almost similar in both group I and II (60% vs 70%). In conclusion, estradoublesynch and progesterone-based ovsynch protocol can effectively induce ovulatory estrus and improve pregnancy rates in delayed pubertal buffalo heifers.

A data-mining approach for developing site-specific fertilizer response functions across the wheat-growing environments in Ethiopia

Summary The use of chemical fertilizers is among the main innovations brought by the 1960s Green Revolution. In Ethiopia, fertilizer application during the last four decades has led to significant yield gains, yet yield remains below its potential across much of the country. One of the main challenges responsible for low yield response to fertilizer application has been the use of ‘blanket’ recommendations, whereby no tailoring of fertilizer amount and frequency is done based on soil requirements. As a result, the amount of fertilizer applied ranges widely, and can be either sub- or supra-optimal. There is thus an increasing need for site-specific fertilizer recommendations which take into account site characteristics such as climate variables (temperature, rainfall, and solar radiation); soil factors (soil organic carbon, moisture, pH, texture, cation exchange capacity, and level of macro- and micronutrients); and topographic position indices. This article reports on a data-mining approach we developed on a large dataset of 6585 wheat (Triticum aestivum) field trials. The dataset includes detailed, site-specific biophysical variables to create nutrient response functions that can guide optimal site-specific fertilizer application. The approach used a machine-learning model (random forest) to capture the relationship between nutrients – nitrogen (N), phosphorous (P), potassium (K), and sulfur (S) – and wheat yield. The model explained about 83, 82, 47, and 69% of variances of yield for N, P, K, and S omission, respectively, with consistent performance across training and testing datasets. Expectedly, for N and P omission data, the most important explanatory variables are nutrient rate, followed by soil organic carbon and soil pH. For K and S, however, climatic variables played an important role alongside nutrient rates. The site-specific yield–fertilizer response curves derived from our model are highly variable from location to location, as they are affected by the climatic, soil, or topographic conditions of the site. Importantly, using principal component analysis, we showed that the shape of the fertilizer response curves is a result of the multiple environmental factors (including soil, topography, and climate) that are at play at a given site, rather than of a specific dominant one. The research output is expected to respond to the national policy demands for a sound method to identify the optimal fertilizer rate to increase economic returns of fertilizer investments and take fertilizer utilization research one step further.

Responses of Soil Fertility and Microbiomes of Atrazine Contaminated Soil to Remediation by Hydrochar and Persulfate

Responses of Soil Fertility and Microbiomes of Atrazine Contaminated Soil to Remediation by Hydrochar and Persulfate

Physiological studies and nutrient accumulation in mustard varieties in response tofertilizer doses under saline condition in semi-arid region of northwestern Haryana

Physiological studies and nutrient accumulation in mustard varieties in response tofertilizer doses under saline condition in semi-arid region of northwestern Haryana

Using Monte Carlo Simulations to Achieve the Best Response From Nitrogen on Grazed Pasture Under a Legislated Nitrogen Cap in New Zealand: A Review

Highlights The benefits of split applications (or more applications at lower application rates) of N fertilizer on pasture have often been espoused without the support of statistical evidence. Provides some clarity on the benefits of split applications of N fertilizer. Explains why low application rates work in situations where accurate spreading is not required. Abstract. Pastoral and crop farming systems have traditionally used the application of nitrogen (N) to achieve an optimal economic production response. This nitrogen response is estimated from an exponential function that approaches an asymptote, which is typical of most fertilizer response curves. The optimal economic N response is often achieved when application rates are greater than plant utilization rates, often resulting in leaching, nitrogen run-off, and volatilization of nitrogenous compounds. These losses can have an impact on freshwater quality and contribute to greenhouse gas (GHG) emissions. In New Zealand, urine from N-fertilized pasture grazed by dairy cattle has been shown to be the most problematic source of N losses. As part of New Zealand’s National Environmental Standards (NES), a synthetic N cap of 190 kgN ha-1yr-1 on grazed pasture and crops has been implemented to reduce nutrient enrichment of fresh water. This study reviewed the use of multiple split applications of N to improve N fertilizer use efficiency and pasture response and used Monte Carlo simulations to demonstrate improved response to split N applications rather than a single optimal application based on economic response. In addition, spreading accuracy also became less important as all the low-application variation occurred along the steepest part of the response curve where this variation results in added yield. Keywords: Dairy cattle, Fertilizer cap, Monte Carlo simulations, Nitrogen use efficiency, Nutrient management.

On-Site Detection of Nitrogen Content in Maize using Optical Sensor

Nutrients are essential for the growth of plants and they also increase the yield. Among the major nutrients, nitrogen is the most important nutrient for crop growth. The current study aims to estimate chlorophyll content vis-a-vis nitrogen content using different techniques and attempts to establish comparative benefits among available techniques. Maize crop being highly known for fertilizer responsiveness was chosen to carry out experiments with different levels of nitrogenous fertilizers. A preliminary field survey was taken in the farmer's field in Coimbatore and Salem districts. Two field experiments and one pot culture experiment at different doses of nitrogen input were conducted in 2019, 2020, and 2021 in the Department of Nano science and Technology at Tamil Nadu Agricultural University. In this study conventional nitrogen was applied with various dosage viz.,0 kgha-1(T1), 50 kgha-1 (T2), 100 kgha-1 (T3), 150 kgha-1 (T4), 200 kgha-1 (T5), 250 kgha-1 (T6), 300 kgha-1 (T7). In the pot culture experiment, IFFCO Nano nitrogen was sprayed on the maize leaves with seven different doses which were control (no spray) (T1), conventional nitrogen (T2), 0.5X RDF(Recommended Dose of Fertilizer) (T3), 1.0X RDF (T4), 1.5X RDF (T5), 2.0X RDF (T6), 2.5X RDF (T7). The chlorophyll content in all the trials were estimated using Dimethyl sulfoxide(DMSO), a portable in-house developed nutrient meter, and Spectroradio meter method. Chlorophyll content was measured at two different growth stages of maize viz., 60 & 90 days after sowing. The total nitrogen was analysed using Kjeldahl method in the maize leaf. Among the treatments, with different doses of nitrogen levels, 300 kgha-1 RDN & 2.5X RDF (T7) recorded higher SPAD (Soil Plant Analysis Development) values, chlorophyll “a” and chlorophyll “b” content and total nitrogen content at 60 DAS (Days After Sowing) in all tested methods. Chlorophyll and total nitrogen content were significantly decreased in later days. In a stressed environment with no nitrogen (T1) applied condition the chlorophyll and nitrogen content showed significantly lower levels

A data-mining approach for developing site-specific fertilizer response functions across the wheat-growing environments in Ethiopia – CORRIGENDUM

A data-mining approach for developing site-specific fertilizer response functions across the wheat-growing environments in Ethiopia – CORRIGENDUM

On the application of the Mitscherlich-Baule equation to fertiliser response data

Abstract The application of the Mitscherlich-Baule equation to fertiliser response data from an extant experiment conducted in New Zealand is further investigated. An estimate of the relevant soil nutrient is obtained as a function of the fitted parameter values using a full model. Estimates of the Baule units are given. These also depend on the fitted parameters. Additionally, predicted estimates of asymptotes are compared with their fitted estimates. Thus, our primary purpose is to describe additional facets of using a Mitscherlich response function to fit crop yield data. We believe the extra results obtained enhance the value of crop growth experiments.

Indian Agriculture needs a Strategic Shift for Improving Fertilizer Response and Overcome Sluggish Foodgrain Production

In India, loss of fertility through soil erosion is primarily a summer monsoons mediated phenomenon. Reversing the land degradation processes contribute to water availability, soil fertility maintenance, adapting to climate change and overall food security. Whereas kharif (monsoon/rainy season crop) foodgrain production largely depends on summer monsoons, the rabi season (post-rainy season/winter crop) rainfall is too little to exert a direct influence. In spite of larger acreage under kharif foodgrain crops, total fertiliser consumption during kharif and rabi seasons is comparable. Negative rainfall anomalies (deficit) adversely affected total fertiliser consumption and their use efficiency. Despite significant differences in fertiliser application rates, the response to applied fertiliser nutrients is almost similar in the two seasons. This implies that nutrient use efficiency (NUE) has a ‘manageable’ and an ‘unmanageable’ component wherein 4R practices are difficult to implement under unfavourable kharif weather conditions. Partial factor productivity of fertilizer nutrients (PFPF) has continuously declined over decades mainly because of depletion of soil organic carbon, imbalanced use of nutrients and inability to maintain soil moisture supplies. These observations plus yield-gap analysis permitted us to conclude that past trends of declining NUE can only be reversed through a shift either in sustainable land management practices or enhancing the genetic yield potential/ biomass of crop cultivars or by combining both and making kharif crop planting independent of monsoons rains through direct dry seeding.

Impact of foreign domestic workers on the fertility decision of households: evidence from Hong Kong

AbstractA potential solution to low fertility is the employment of foreign domestic workers (FDWs), who substitute child-rearing and housework duties, thus reducing child-rearing costs. Recent studies argue that the flow of low-skilled foreign workers into the childcare sector influences fertility choice. However, these studies mainly use the availability of FDWs in the local area as the causal inference and focus on Western countries, making it difficult to identify individual direct effects or generalize the findings to other countries. To bridge this research gap and examine the impacts, this study uses household data from the Hong Kong census. Employing ordinary least squares, the inverse probability weighted regression adjustment, and the instrumental variable approach, we find that households that employ live-in FDWs give birth to more children. Moreover, the heterogeneous analysis reveals that women's greater proportional contribution to household income has a positive impact on households' fertility response after employing the FDWs.

CHARACTERISTICS EVALUATION, NUTRITION CONTRIBUTION OF IRRIGATION WATER AND STRAW TOWARD RESPONSE TO NUTRITIONAL POTASSIUM FERTILIZATION IN PADDY FIELD

Potassium is one of the primary macro nutrients along with N and P nutrients, which plants need in large quantities. Lack of K nutrients, one of which can inhibit photosynthetic transport to plant seeds. The availability of K nutrients in paddy soil varies greatly depending on the chemical properties of other soils. This paper aims to evaluate the nutrient K characteristics of paddy fields, the K contribution from irrigation water and harvested straw, and the response of fertilization to rice yields. The availability of K nutrients, apart from being influenced by clay mineral composition, clay content, organic C and soil CEC, is also influenced by N fertilization, soil pH, exchangeable of Ca and Mg, and N-total. The content of potential K and exchangeable of K increases in paddy fields which are further east of Java Island because they have soil with parent material that is rich in potassium minerals. The content of exchangeable K is very closely related to the potential K with R2 = 0.53 (n = 73). Based on the map of the nutrient status of K rice fields with a scale of 1:250,000 in 23 provinces in Indonesia, it is known that most of the paddy fields have moderate K status at 37% and high 48%. The K content in paddy soil can be contributed by irrigation water as much as 7-74 kg K/ha/season. If all of the remaining rice straw from crop yields is returned to the field, the K nutrient requirements for rice plants in the medium and high K nutrient status fields have been fulfilled. The response to K fertilization in rice plants was only visible when the exchangeable K content < 0.10 cmol(+)/ kg. The policy implication of this paper is that K fertilization is focused on paddy fields with low K content, the effectiveness of K fertilization can be increased by returning rice straw from crop residues and proper N fertilization.